{"items":[{"id":"NVI-00009111","kind":"vulnerability","title":"Tornado: Quadratic CPU usage when parsing HTTP headers with line folding","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-pcg2-g6cj-q92c","CVE-2026-116577"],"plain_summary":"GitHub lists this reviewed advisory for tornado. 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-409af165f7605b278fb1ec872f6458d7"],"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":"2026-10-28T22:43:44.000Z","value":"5.3 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-b5261f0e8ce1b362ab96c3c433116ad7"},{"kind":"EPSS","as_of":"2026-11-01T12:00:16.000Z","value":"0.384%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.32454. Missing scores are unknown.","source_id":"sr-409af165f7605b278fb1ec872f6458d7"}],"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-b5261f0e8ce1b362ab96c3c433116ad7","url":"https://github.com/advisories/GHSA-pcg2-g6cj-q92c","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-pcg2-g6cj-q92c","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T21:56:08.420Z"},{"id":"sr-409af165f7605b278fb1ec872f6458d7","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-2026-116577","publisher":"FIRST EPSS","observed_at":"2026-11-01T14:28:32.267Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-b5261f0e8ce1b362ab96c3c433116ad7"],"technology":"tornado","known_exclusions":[],"conditions_summary":"### Summary\n\nTornado's HTTP header parser takes quadratic time (O(n²)) when a header value is continued across many \"obsolete line folding\" (obs-fold) lines. An unauthenticated attacker can send a request whose header block is mostly short continuation lines. Parsing it uses a large amount of CPU on the IOLoop thread and blocks every other connection that process is serving.\n\nThis issue is closely related to CVE-2025-67725 (GHSA-c98p-7wgm-6p64). The fix for that advisory covered repeated headers but not line-folded continuations.\n\n### Impact\n\nAll Tornado HTTP servers are affected. Header parsing runs before any application code, so no authentication or particular handler is required.\n\nHow bad it gets depends on `max_header_size`:\n\n- **Default (64 KB):** each malicious request blocks the event loop for tens of milliseconds. Repeated requests can degrade service.\n- **Raised `max_header_size`:** the cost grows with the square of the header size. A single 1 MB request can block the process for several seconds.\n\nOnly availability is affected. Confidentiality and integrity are not.\n\n### Patches\n\nFixed in Tornado 6.6 by removing support for obsolete line folding completely; header lines t","public_affected_ranges":["< 6.6"]}],"null_published_at":"2026-11-08T19:53:48.774Z","source_updated_at":"2026-10-28T22:43:44.000Z","source_disclosed_at":"2026-10-28T22:43:41.000Z","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":"2026-10-31T21:56:08.420Z"},{"id":"NVI-00009111","kind":"vulnerability","title":"Tornado: Quadratic CPU usage when parsing HTTP headers with line folding","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-pcg2-g6cj-q92c","CVE-2026-116577"],"plain_summary":"GitHub lists this reviewed advisory for tornado. 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-b5261f0e8ce1b362ab96c3c433116ad7"],"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":"2026-10-28T22:43:44.000Z","value":"5.3 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-b5261f0e8ce1b362ab96c3c433116ad7"}],"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-b5261f0e8ce1b362ab96c3c433116ad7","url":"https://github.com/advisories/GHSA-pcg2-g6cj-q92c","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-pcg2-g6cj-q92c","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T21:56:08.420Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-b5261f0e8ce1b362ab96c3c433116ad7"],"technology":"tornado","known_exclusions":[],"conditions_summary":"### Summary\n\nTornado's HTTP header parser takes quadratic time (O(n²)) when a header value is continued across many \"obsolete line folding\" (obs-fold) lines. An unauthenticated attacker can send a request whose header block is mostly short continuation lines. Parsing it uses a large amount of CPU on the IOLoop thread and blocks every other connection that process is serving.\n\nThis issue is closely related to CVE-2025-67725 (GHSA-c98p-7wgm-6p64). The fix for that advisory covered repeated headers but not line-folded continuations.\n\n### Impact\n\nAll Tornado HTTP servers are affected. Header parsing runs before any application code, so no authentication or particular handler is required.\n\nHow bad it gets depends on `max_header_size`:\n\n- **Default (64 KB):** each malicious request blocks the event loop for tens of milliseconds. Repeated requests can degrade service.\n- **Raised `max_header_size`:** the cost grows with the square of the header size. A single 1 MB request can block the process for several seconds.\n\nOnly availability is affected. Confidentiality and integrity are not.\n\n### Patches\n\nFixed in Tornado 6.6 by removing support for obsolete line folding completely; header lines t","public_affected_ranges":["< 6.6"]}],"null_published_at":"2026-10-31T22:13:31.284Z","source_updated_at":"2026-10-28T22:43:44.000Z","source_disclosed_at":"2026-10-28T22:43:41.000Z","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":"2026-10-31T21:56:08.420Z"}],"next_cursor":null,"snapshot_revision":"42594"}