CVE-2026-107722 fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion

fast-jwt provides fast JSON Web Token JWT implementation. From 6.2.0 until 6.3.0, fast-jwt can misclassify RSA public-key text as an HMAC secret when the key has non-whitespace content before its PEM header. In src/crypto.js, performDetectPublicKeyAlgorithms trims whitespace but publicKeyPemMatch...

CVE-2026-107722

The fast-jwt library (versions 6.2.0 to 6.3.0 ) is vulnerable to RSA→HS256 algorithm confusion due to an incomplete patch of CVE-2026-34950. The root cause resides in src/crypto.js, where performDetectPublicKeyAlgorithms trims whitespace but publicKeyPemMatcher remains start-anchored. This allows...

CVE-2026-107722 fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion

fast-jwt provides fast JSON Web Token JWT implementation. From 6.2.0 until 6.3.0, fast-jwt can misclassify RSA public-key text as an HMAC secret when the key has non-whitespace content before its PEM header. In src/crypto.js, performDetectPublicKeyAlgorithms trims whitespace but publicKeyPemMatch...

CVE-2026-107722 fast-jwt: Incomplete patch of CVE-2026-34950: Non-whitespace key-prefix re-enables RSA→HS256 algorithm confusion

fast-jwt provides fast JSON Web Token JWT implementation. From 6.2.0 until 6.3.0, fast-jwt can misclassify RSA public-key text as an HMAC secret when the key has non-whitespace content before its PEM header. In src/crypto.js, performDetectPublicKeyAlgorithms trims whitespace but publicKeyPemMatch...

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...

CVE-2026-34950: Use of a Broken or Risky Cryptographic Algorithm

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...

CVE-2023-48223

fast-jwt provides fast JSON Web Token JWT implementation. Prior to version 3.3.2, the fast-jwt library does not properly prevent JWT algorithm confusion for all public key types. The 'publicKeyPemMatcher' in 'fast-jwt/src/crypto.js' does not properly match all common PEM formats for public keys. ...

CVE-2023-48223: Improper Input Validation

fast-jwt provides fast JSON Web Token JWT implementation. Prior to version 3.3.2, the fast-jwt library does not properly prevent JWT algorithm confusion for all public key types. The 'publicKeyPemMatcher' in 'fast-jwt/src/crypto.js' does not properly match all common PEM formats for public keys. ...