CVE-2026-34950

fast-jwt provides fast JSON Web Token JWT implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patch...

CVE-2026-34950 fast-jwt has an incomplete fix for CVE-2023-48223: JWT Algorithm Confusion via Whitespace-Prefixed RSA Public Key

fast-jwt provides fast JSON Web Token JWT implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patch...

JSON Web Token (JWT) Algorithm Confusion

fast-jwt is vulnerable to JWT Algorithm Confusion. The vulnerability is caused by a missing validation on publicKeyPemMatcher constant defined in fast-jwt/src/crypto.js which is used to match all common PEM formats for public keys. An attacker can craft a malicious JWT token utilizing the HS256...