CVE-2026-35041
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.
Does this matter?
Lower severity and a low EPSS score (0.26%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.26% probability · 18th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-1333
- Affected
- nearform/fast-jwt
- Source
- security-advisories@github.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.