{"id":"CVE-2026-121437","published":"2026-11-03T15:17:35.147","lastModified":"2026-11-03T17:18:09.653","description":"Mistune from 3.3.0 before 3.3.4 contains a denial of service vulnerability that allows remote attackers to exhaust CPU through quadratic-time emphasis delimiter processing. Attackers can submit small markdown documents with repeated patterns like \"*a_b\" to trigger an O(n²) index-fixup loop, stalling workers for seconds.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-407"],"vendors":[],"products":[],"references":[{"url":"https://github.com/lepture/mistune/commit/b4dd3284e52ec741ed9a227db29ade9017828e90","tags":[]},{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-qp42-r9j6-83g9","tags":[]},{"url":"https://www.vulncheck.com/advisories/mistune-3.3.0-before-3.3.4-quadratic-time-dos-via-process-emphasis-delimiters","tags":[]},{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-qp42-r9j6-83g9","tags":[]}],"exploitRefs":[{"url":"https://github.com/lepture/mistune/commit/b4dd3284e52ec741ed9a227db29ade9017828e90","tags":[]},{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-qp42-r9j6-83g9","tags":[]},{"url":"https://github.com/lepture/mistune/security/advisories/GHSA-qp42-r9j6-83g9","tags":[]}],"hasPoc":true,"ai":null}