Antonio Attanasio

3 exploits Active since Apr 2026
CVE-2026-35040 WRITEUP MEDIUM WRITEUP
fast-jwt: Stateful RegExp (/g or /y) causes non-deterministic allowed-claim validation (logical DoS)
fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.1, using certain modifiers on RegExp objects in the allowedAud, allowedIss, allowedSub, allowedJti, or allowedNonce options in verify functions can cause certain unintended behaviours. This is because some modifiers are stateful and will cause failures in every second verification attempt regardless of the validity of the token provided. Such modifiers are /g (global matching) and /y (sticky matching). This does NOT allow invalid tokens to be accepted, only for valid tokens to be improperly rejected in some configurations. Instead it causes 50% of valid authentication requests to fail in an alternating pattern. This vulnerability is fixed in 6.2.1.
CVSS 5.3
CVE-2026-35041 WRITEUP MEDIUM WRITEUP
ReDoS in fast-jwt when using RegExp in allowed* leading to CPU exhaustion during token verification
fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is attacker-controlled and the library evaluates it against the supplied RegExp, a crafted JWT can trigger catastrophic backtracking in the JavaScript regex engine, resulting in significant CPU consumption during verification. This vulnerability is fixed in 6.2.1.
CVSS 4.2
CVE-2026-35039 WRITEUP CRITICAL WRITEUP
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 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.
CVSS 9.1