CVE-2026-35042: Nearform Fast-Jwt

High severity, CVSS 7.5. EPSS: 0.2% chance of exploitation in the next 30 days.

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, fast-jwt does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that fast-jwt does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC.

Affected products

• Nearform Fast-Jwt: before 6.2.0 (fixed in 6.2.0)

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