{"id":"CVE-2026-35041","aliases":["GHSA-cjw9-ghj4-fwxf"],"url":"https://o3.security/vulnerability/CVE-2026-35041","summary":"ReDoS in fast-jwt when using RegExp in allowed* leading to CPU exhaustion during token verification","details":"fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is attacker-controlled and the library evaluates it against the supplied RegExp, a crafted JWT can trigger catastrophic backtracking in the JavaScript regex engine, resulting in significant CPU consumption during verification. This vulnerability is fixed in 6.2.1.","published":"2026-04-09T14:55:22.807Z","modified":"2026-08-12T03:51:29.054115779Z","cvss":{"score":4.2,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"fast-jwt","fixedVersion":"6.2.1"}],"fix":{"url":"https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94","label":"nearform/fast-jwt@b0be0ca"},"references":[{"type":"WEB","url":"https://github.com/nearform/fast-jwt/releases/tag/v6.2.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35041.json"},{"type":"ADVISORY","url":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-35041"},{"type":"FIX","url":"https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94"},{"type":"FIX","url":"https://github.com/nearform/fast-jwt/pull/595"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:29.054115779Z"}}