{"id":"CVE-2026-91991","revision":"784d28736c0e4b2587a5a1d412032dae","records":[{"revision":"784d28736c0e4b2587a5a1d412032dae","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-91991","aliases":[],"title":"Tornado before 6.5.8 Cookie Attribute Injection via Capitalized kwargs","description":"Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.","state":0,"publishedAt":"2026-09-15T15:18:32.408+00:00","modifiedAt":"2026-10-08T15:26:01.123+00:00","affected":[{"ecosystem":"Vendor product","name":"tornado","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"tornadoweb\",\n                    \"product\": \"tornado\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"versions\": [\n                        {\n                            \"versionType\": \"semver\",\n                            \"version\": \"6.5.5\",\n                            \"lessThan\": \"6.5.8\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"versionType\": \"semver\",\n                            \"version\": \"6.5.8\",\n                            \"status\": \"unaffected\"\n                        }\n                    ],\n                    \"packageURL\": \"pkg:pypi/tornado\"\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N","score":6.3,"severity":"MEDIUM"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N","score":5.4,"severity":"MEDIUM"}],"references":["https://github.com/tornadoweb/tornado/security/advisories/GHSA-wwv5-g3v4-889x","https://www.vulncheck.com/advisories/tornado-before-6.5.8-cookie-attribute-injection-via-capitalized-kwargs"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-91991","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-91991","identifiers":["CVE-2026-91991"]},"retained":false,"historicalAffected":[]}],"coverage":[]}