CVE-2026-35039
fast-jwt Affected by Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)
CRITICAL 9.1EPSS 0.2%
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
- nearform · fast-jwt
- CVSS v3.1 GITHUB
- 9.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS
- 0.22% chance of exploitation in the next 30 days, 12th percentile
- Published
- 2026-04-06
- Updated
- 2026-05-13
Proof-of-concept exploits (1)
Security advisories
- nearform/fast-jwt/security/advisories/GHSA-rp9m-7r4c-75qg
- nearform/fast-jwt/commit/de121056c6415b58770c60640881eaec67ac4ceb