Vulnerability Details CVE-2026-35041
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 8.6%
CVSS Severity
CVSS v3 Score 4.2
References
- https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94
- https://github.com/nearform/fast-jwt/pull/595
- https://github.com/nearform/fast-jwt/releases/tag/v6.2.1
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf