CVE-2026-35039

CRITICAL9.1

fast-jwt Affected by Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)

Published Apr 6, 2026

Modified 2 weeks ago

Details

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.

References

WEB

https://github.com/nearform/fast-jwt/commit/de121056c6415b58770c60640881eaec67ac4ceb

WEB

https://github.com/nearform/fast-jwt/security/advisories/GHSA-rp9m-7r4c-75qg

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-35039

CVSS Analysis

CVSS v3.1

9.1

Exploitability

Attack Vector