CVE-2026-35039: Nearform Fast-Jwt

Critical severity, CVSS 9.1. EPSS: 0.2% chance of exploitation in the next 30 days.

fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom cacheKeyBuilder method which does not properly create unique keys for different tokens can lead to cache collisions. This could cause tokens to be mis-identified during the verification process leading to valid tokens returning claims from different valid tokens and users being mis-identified as other users based on the wrong token. Version 6.2.0 contains a patch.

Affected products

• Nearform Fast-Jwt: from 0.1.0, before 6.1.0 (fixed in 6.1.0)

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