CVE-2026-35041: Nearform Fast-Jwt

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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 products

• Nearform Fast-Jwt: from 5.0.0, before 6.2.1 (fixed in 6.2.1)

Published 2026-04-09. Last modified 2026-06-17.