CVE-2026-107724
highfast-jwt provides fast JSON Web Token (JWT) implementation.
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.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Affected products
Not reported by the source (unknown — not "none").
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://github.com/nearform/fast-jwt/commit/10f9591349199ed2ab9fa1748ce92cdca697f6cf security-advisories@github.com
- https://github.com/nearform/fast-jwt/pull/636 security-advisories@github.com
- https://github.com/nearform/fast-jwt/releases/tag/v6.3.0 security-advisories@github.com
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx security-advisories@github.com
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx 134c704f-9b21-4f2e-91b3-4a467353bcc0