{"id":"CVE-2026-35041","state":"PUBLISHED","title":"ReDoS in fast-jwt when using RegExp in allowed* leading to CPU exhaustion during token verification","description":"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.","publishedAt":"2026-04-09T14:55:22.807Z","updatedAt":"2026-04-09T16:15:25.352Z","severity":{"score":4.2,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["nearform fast-jwt"],"affected":[{"vendor":"nearform","product":"fast-jwt","versions":[{"version":">= 5.0.0, < 6.2.1","status":"affected"}]}],"references":["https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf","https://github.com/nearform/fast-jwt/pull/595","https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94","https://github.com/nearform/fast-jwt/releases/tag/v6.2.1"],"weaknesses":["CWE-1333"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/35xxx/CVE-2026-35041.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-35041","state":"PUBLISHED","datePublished":"2026-04-09T14:55:22.807Z","dateUpdated":"2026-04-09T16:15:25.352Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-31T21:06:06.428Z"},"containers":{"cna":{"title":"ReDoS in fast-jwt when using RegExp in allowed* leading to CPU exhaustion during token verification","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"nearform","product":"fast-jwt","versions":[{"version":">= 5.0.0, < 6.2.1","status":"affected"}]}],"references":[{"url":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf","name":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/nearform/fast-jwt/pull/595","name":"https://github.com/nearform/fast-jwt/pull/595","tags":["x_refsource_MISC"]},{"url":"https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94","name":"https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94","tags":["x_refsource_MISC"]},{"url":"https://github.com/nearform/fast-jwt/releases/tag/v6.2.1","name":"https://github.com/nearform/fast-jwt/releases/tag/v6.2.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":4.2,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"HIGH","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1333","lang":"en","description":"CWE-1333: Inefficient Regular Expression Complexity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-04-09T14:55:22.807Z"},"source":{"advisory":"GHSA-cjw9-ghj4-fwxf","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-09T16:14:14.434470Z","id":"CVE-2026-35041","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-09T16:15:25.352Z"}}]}}}