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.
Metrics
CVSS 3.1 6.5/10
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| nearform | fast-jwt | >= 5.0.0, < 6.2.1 |
References
- https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94Patch
- https://github.com/nearform/fast-jwt/pull/595Issue Tracking, Patch
- https://github.com/nearform/fast-jwt/releases/tag/v6.2.1Product, Release Notes
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxfExploit, Mitigation, Vendor Advisory
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxfExploit, Mitigation, Vendor Advisory
Timeline
- Published
- Apr 9, 2026
- Last modified
- Oct 26, 2026
- NVD status
- Analyzed