CVE-2026-35039 fast-jwt Affected by Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)

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 proce...

CVE-2026-35039 fast-jwt Affected by Cache Confusion via cacheKeyBuilder Collisions Can Return Claims From a Different Token (Identity/Authorization Mixup)

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 proce...

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

NOTE: While the library exposes a mechanism which could introduce the vulnerability, this issue is created by developer-supplied code and not by the library itself. We will add a warning and some education for users around the possible issues however since the defaults work we will not be updatin...