CVE-2026-35041 — 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 conf…
Published: 2026-04-09 · CVSS: 4.2 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7