جزئیات آسیب‌پذیری

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.2.4, fast-jwt can classify raw serialized public JWK or JWKS JSON as an HMAC secret because src/crypto.js performDetectPublicKeyAlgorithms treats non-PEM strings as symmetric key material. If HS256 is explicitly allowed or inferred, an attacker who knows the exact serialized public-key bytes can use those bytes as an HMAC key and create a token containing arbitrary claims that createVerifier accepts. Serialization ordering or whitespace differences can prevent exploitation, and applications using supported PEM keys with an asymmetric-only algorithm allowlist are not affected. This issue is fixed in version 6.3.0.

• https://github.com/nearform/fast-jwt/pull/636 x_refsource_MISC
• https://github.com/nearform/fast-jwt/commit/10f9591349199ed2ab9fa1748ce92cdca697f6cf x_refsource_MISC
• https://github.com/nearform/fast-jwt/releases/tag/v6.3.0 x_refsource_MISC
• https://github.com/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx x_refsource_CONFIRM