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OpenAdvisories
Critical · 9.1 CVE-2026-35039 EUVD-2026-19380GHSA-rp9m-7r4c-75qg

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

Published Apr 6, 2026 · Updated May 13, 2026 · Assigned by GitHub_M

Description

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

VendorProductAffectedFixed
nearform fast-jwt >= 0.0.1, < 6.2.0 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm fast-jwt >= 0.0.1, < 6.2.0 6.2.0 GHSA-rp9m-7r4c-75qg

References