{"items":[{"id":"NVI-00008214","kind":"vulnerability","title":"Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion (\"Billion Laughs\")","revision":4,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected.","NVD lastModified does not establish freshness of every associated CPE record."],"lifecycle":"active","identifiers":["GHSA-4qpc-3hr4-r2p4","CVE-2026-45304"],"plain_summary":"GitHub lists this reviewed advisory for symfony/yaml, symfony/symfony, symfony/symfony, symfony/symfony, symfony/symfony. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-822016a69c45555643ce49209096e3c9"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-07-15T14:55:30.250Z","value":"7.5 HIGH (3.1)","meaning":"nvd@nist.gov severity; no combined Null risk score.","source_id":"sr-124f2f30c47b23465adaa9b0dbf451ce"},{"kind":"CVSS","as_of":"2026-07-15T14:55:30.250Z","value":"8.7 HIGH (4.0)","meaning":"security-advisories@github.com severity; no combined Null risk score.","source_id":"sr-124f2f30c47b23465adaa9b0dbf451ce"},{"kind":"EPSS","as_of":"2026-10-31T12:00:27.000Z","value":"0.684%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.52585. Missing scores are unknown.","source_id":"sr-822016a69c45555643ce49209096e3c9"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-6d351c2c9cf14cc7b854b23e96e91f4e","url":"https://github.com/advisories/GHSA-4qpc-3hr4-r2p4","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-4qpc-3hr4-r2p4","publisher":"GitHub Advisory Database","observed_at":"2026-11-07T00:53:22.747Z"},{"id":"sr-fa698f39212e0e22bd4e8d9ec0ef22d3","url":"https://github.com/advisories/GHSA-4qpc-3hr4-r2p4","basis":"vendor_advisory","notes":"GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.","title":"GHSA-4qpc-3hr4-r2p4","publisher":"GitHub Advisory Database via OSV","observed_at":"2026-10-31T21:41:49.672Z"},{"id":"sr-124f2f30c47b23465adaa9b0dbf451ce","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45304","basis":"official_catalog","notes":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","title":"CVE-2026-45304","publisher":"NIST National Vulnerability Database","observed_at":"2026-11-03T22:35:20.969Z"},{"id":"sr-822016a69c45555643ce49209096e3c9","url":"https://www.first.org/epss/data.html","basis":"official_catalog","notes":"FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.","title":"CVE-2026-45304","publisher":"FIRST EPSS","observed_at":"2026-10-31T22:06:15.379Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["< 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["< 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":[">= 6.0.0, < 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":[">= 7.0.0, < 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":[">= 8.0.0, < 8.0.12"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":[">= 6.0.0, < 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":[">= 7.0.0, < 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-6d351c2c9cf14cc7b854b23e96e91f4e"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":[">= 8.0.0, < 8.0.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]}],"null_published_at":"2026-11-08T15:11:47.517Z","source_updated_at":"2026-05-27T21:33:52.000Z","source_disclosed_at":"2026-05-27T21:33:50.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Source facts changed; compare the preserved prior revision.","null_first_observed_at":"2026-10-31T21:41:49.672Z"},{"id":"NVI-00008214","kind":"vulnerability","title":"Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion (\"Billion Laughs\")","revision":3,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected.","NVD lastModified does not establish freshness of every associated CPE record."],"lifecycle":"active","identifiers":["GHSA-4qpc-3hr4-r2p4","CVE-2026-45304"],"plain_summary":"OSV carries this publisher advisory for symfony/yaml, symfony/symfony, symfony/symfony, symfony/symfony, symfony/symfony. This is an aggregated source copy; consult the original publisher and compare update dates.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-822016a69c45555643ce49209096e3c9"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-07-15T14:55:30.250Z","value":"7.5 HIGH (3.1)","meaning":"nvd@nist.gov severity; no combined Null risk score.","source_id":"sr-124f2f30c47b23465adaa9b0dbf451ce"},{"kind":"CVSS","as_of":"2026-07-15T14:55:30.250Z","value":"8.7 HIGH (4.0)","meaning":"security-advisories@github.com severity; no combined Null risk score.","source_id":"sr-124f2f30c47b23465adaa9b0dbf451ce"},{"kind":"EPSS","as_of":"2026-10-31T12:00:27.000Z","value":"0.684%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.52585. Missing scores are unknown.","source_id":"sr-822016a69c45555643ce49209096e3c9"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-fa698f39212e0e22bd4e8d9ec0ef22d3","url":"https://github.com/advisories/GHSA-4qpc-3hr4-r2p4","basis":"vendor_advisory","notes":"GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.","title":"GHSA-4qpc-3hr4-r2p4","publisher":"GitHub Advisory Database via OSV","observed_at":"2026-10-31T21:41:49.672Z"},{"id":"sr-124f2f30c47b23465adaa9b0dbf451ce","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45304","basis":"official_catalog","notes":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","title":"CVE-2026-45304","publisher":"NIST National Vulnerability Database","observed_at":"2026-11-03T22:35:20.969Z"},{"id":"sr-822016a69c45555643ce49209096e3c9","url":"https://www.first.org/epss/data.html","basis":"official_catalog","notes":"FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.","title":"CVE-2026-45304","publisher":"FIRST EPSS","observed_at":"2026-10-31T22:06:15.379Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]}],"null_published_at":"2026-11-04T10:04:35.908Z","source_updated_at":"2026-09-10T03:50:45.630Z","source_disclosed_at":"2026-05-27T21:33:50.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Source facts changed; compare the preserved prior revision.","null_first_observed_at":"2026-10-31T21:41:49.672Z"},{"id":"NVI-00008214","kind":"vulnerability","title":"Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion (\"Billion Laughs\")","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-4qpc-3hr4-r2p4","CVE-2026-45304"],"plain_summary":"OSV carries this publisher advisory for symfony/yaml, symfony/symfony, symfony/symfony, symfony/symfony, symfony/symfony. This is an aggregated source copy; consult the original publisher and compare update dates.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-822016a69c45555643ce49209096e3c9"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"EPSS","as_of":"2026-10-31T12:00:27.000Z","value":"0.684%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.52585. Missing scores are unknown.","source_id":"sr-822016a69c45555643ce49209096e3c9"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-fa698f39212e0e22bd4e8d9ec0ef22d3","url":"https://github.com/advisories/GHSA-4qpc-3hr4-r2p4","basis":"vendor_advisory","notes":"GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.","title":"GHSA-4qpc-3hr4-r2p4","publisher":"GitHub Advisory Database via OSV","observed_at":"2026-10-31T21:41:49.672Z"},{"id":"sr-822016a69c45555643ce49209096e3c9","url":"https://www.first.org/epss/data.html","basis":"official_catalog","notes":"FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.","title":"CVE-2026-45304","publisher":"FIRST EPSS","observed_at":"2026-10-31T22:06:15.379Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]}],"null_published_at":"2026-11-03T02:33:09.086Z","source_updated_at":"2026-09-10T03:50:45.630Z","source_disclosed_at":"2026-05-27T21:33:50.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.","null_first_observed_at":"2026-10-31T21:41:49.672Z"},{"id":"NVI-00008214","kind":"vulnerability","title":"Symfony's YAML Parser Vulnerable to Exponential Memory Allocation via Recursive Collection-Alias Expansion (\"Billion Laughs\")","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-4qpc-3hr4-r2p4","CVE-2026-45304"],"plain_summary":"OSV carries this publisher advisory for symfony/yaml, symfony/symfony, symfony/symfony, symfony/symfony, symfony/symfony. This is an aggregated source copy; consult the original publisher and compare update dates.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 5.4.52 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/symfony. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 6.4.40 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 7.4.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null},{"summary":"The original advisory lists fixed boundaries 8.0.12 for symfony/yaml. Confirm the publisher’s latest guidance.","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"action_type":"vendor_patch","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-fa698f39212e0e22bd4e8d9ec0ef22d3","url":"https://github.com/advisories/GHSA-4qpc-3hr4-r2p4","basis":"vendor_advisory","notes":"GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.","title":"GHSA-4qpc-3hr4-r2p4","publisher":"GitHub Advisory Database via OSV","observed_at":"2026-10-31T21:41:49.672Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 0; fixed 5.4.52"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/symfony","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 6.0.0; fixed 6.4.40"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 7.0.0; fixed 7.4.12"]},{"certainty":"source_listed","source_ids":["sr-fa698f39212e0e22bd4e8d9ec0ef22d3"],"technology":"symfony/yaml","known_exclusions":[],"conditions_summary":"### Description\n\n`Symfony\\Component\\Yaml\\Parser` resolves YAML aliases (`*anchor`) during parsing. Aliases that reference *collections* (arrays, `stdClass`, `TaggedValue`-wrapped collections) can themselves point to other collections containing aliases, creating exponential expansion at resolution time. A small input can blow up into a multi-gigabyte structure and exhaust memory: the classic \"Billion Laughs\" denial-of-service against any parser exposed to untrusted YAML.\n\n### Resolution\n\nThe `Parser` now counts collection alias resolutions in a shared `ParserState` object, with a default limit of **128**, following the SnakeYAML model. Scalar aliases remain unrestricted since they cannot drive exponential growth. The limit is configurable via a new `$maxAliasesForCollections` argument on `Parser::__construct()`, `Yaml::parse()` and `Yaml::parseFile()`. A new `Yaml::PARSE_EXCEPTION_ON_ALIAS` flag also rejects all aliases outright when parsing fully untrusted input.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/e77391b2e4f18821198f010d573","public_affected_ranges":["ECOSYSTEM: introduced 8.0.0; fixed 8.0.12"]}],"null_published_at":"2026-10-31T22:13:22.834Z","source_updated_at":"2026-09-10T03:50:45.630Z","source_disclosed_at":"2026-05-27T21:33:50.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-10-31T21:41:49.672Z"}],"next_cursor":null,"snapshot_revision":"42594"}