{"items":[{"id":"NVI-00006448","kind":"vulnerability","title":"MCP PHP SDK: client HttpTransport SSE buffer (sseBuffer .= chunk) grows unbounded when server withholds the event delimiter","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-7m52-jw36-44r3","CVE-2026-53965"],"plain_summary":"OSV carries this publisher advisory for mcp/sdk. 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 0.7.1 for mcp/sdk. Confirm the publisher’s latest guidance.","source_ids":["sr-b5538fd180c0dd1745341194f475961e"],"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-bfef36f674b3f3e4a3833986657f3c85"],"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":"0.615%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.49472. Missing scores are unknown.","source_id":"sr-bfef36f674b3f3e4a3833986657f3c85"}],"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-b5538fd180c0dd1745341194f475961e","url":"https://github.com/advisories/GHSA-7m52-jw36-44r3","basis":"vendor_advisory","notes":"GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.","title":"GHSA-7m52-jw36-44r3","publisher":"GitHub Advisory Database via OSV","observed_at":"2026-10-31T21:41:59.951Z"},{"id":"sr-bfef36f674b3f3e4a3833986657f3c85","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-2026-53965","publisher":"FIRST EPSS","observed_at":"2026-10-31T22:06:15.382Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-b5538fd180c0dd1745341194f475961e"],"technology":"mcp/sdk","known_exclusions":[],"conditions_summary":"## Summary\n\nThe HTTP client transport in `mcp/sdk` reads a Server-Sent-Events (SSE) response\nstream incrementally and appends each 4 KiB chunk to an in-memory buffer\n(`$this->sseBuffer .= $chunk;`) with **no upper bound**. The buffer is only ever\nflushed when an SSE event delimiter (`\"\\n\\n\"`) appears. A remote MCP server (the\npeer the client connects to) that streams response bytes without ever sending the\n`\"\\n\\n\"` delimiter makes `$sseBuffer` grow without limit until the client process\nexhausts its PHP `memory_limit` (fatal \"Allowed memory size … exhausted\") or is\nkilled by the OS OOM-killer.\n\nThis is a denial-of-service against the MCP **client**: any server it talks to —\nor a network position that controls the server's response body — can crash the\nclient by withholding the event delimiter while streaming data.\n\n## Impact\n\n- **Type:** Denial of service (memory exhaustion / process crash) of the MCP client.\n- **Who can trigger it:** The remote MCP server endpoint the client connects to via\n  `HttpTransport`, or any party that can control/inject into that server's SSE\n  response body (e.g. a man-in-the-middle on a plaintext endpoint, or a malicious\n  or compromised server). The bu","public_affected_ranges":["ECOSYSTEM: introduced 0.5.0; fixed 0.7.1"]}],"null_published_at":"2026-11-06T21:03:48.006Z","source_updated_at":"2026-08-19T19:33:55.087Z","source_disclosed_at":"2026-08-19T19:17:49.000Z","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":"2026-10-31T21:41:59.951Z"},{"id":"NVI-00006448","kind":"vulnerability","title":"MCP PHP SDK: client HttpTransport SSE buffer (sseBuffer .= chunk) grows unbounded when server withholds the event delimiter","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-7m52-jw36-44r3","CVE-2026-53965"],"plain_summary":"OSV carries this publisher advisory for mcp/sdk. 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 0.7.1 for mcp/sdk. Confirm the publisher’s latest guidance.","source_ids":["sr-b5538fd180c0dd1745341194f475961e"],"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-b5538fd180c0dd1745341194f475961e","url":"https://github.com/advisories/GHSA-7m52-jw36-44r3","basis":"vendor_advisory","notes":"GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.","title":"GHSA-7m52-jw36-44r3","publisher":"GitHub Advisory Database via OSV","observed_at":"2026-10-31T21:41:59.951Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-b5538fd180c0dd1745341194f475961e"],"technology":"mcp/sdk","known_exclusions":[],"conditions_summary":"## Summary\n\nThe HTTP client transport in `mcp/sdk` reads a Server-Sent-Events (SSE) response\nstream incrementally and appends each 4 KiB chunk to an in-memory buffer\n(`$this->sseBuffer .= $chunk;`) with **no upper bound**. The buffer is only ever\nflushed when an SSE event delimiter (`\"\\n\\n\"`) appears. A remote MCP server (the\npeer the client connects to) that streams response bytes without ever sending the\n`\"\\n\\n\"` delimiter makes `$sseBuffer` grow without limit until the client process\nexhausts its PHP `memory_limit` (fatal \"Allowed memory size … exhausted\") or is\nkilled by the OS OOM-killer.\n\nThis is a denial-of-service against the MCP **client**: any server it talks to —\nor a network position that controls the server's response body — can crash the\nclient by withholding the event delimiter while streaming data.\n\n## Impact\n\n- **Type:** Denial of service (memory exhaustion / process crash) of the MCP client.\n- **Who can trigger it:** The remote MCP server endpoint the client connects to via\n  `HttpTransport`, or any party that can control/inject into that server's SSE\n  response body (e.g. a man-in-the-middle on a plaintext endpoint, or a malicious\n  or compromised server). The bu","public_affected_ranges":["ECOSYSTEM: introduced 0.5.0; fixed 0.7.1"]}],"null_published_at":"2026-10-31T22:13:10.057Z","source_updated_at":"2026-08-19T19:33:55.087Z","source_disclosed_at":"2026-08-19T19:17:49.000Z","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":"2026-10-31T21:41:59.951Z"}],"next_cursor":null,"snapshot_revision":"42594"}