CVE-2026-107723
highfast-jwt provides fast JSON Web Token (JWT) implementation.
fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject arrays. The claim validator loop then finds no named exp, nbf, iss, aud, sub, jti, or nonce properties and silently skips those configured checks, returning the array as a successfully verified payload. An attacker who can produce or influence a validly signed token may bypass expiry, issuer, audience, subject, revocation, and replay protections. The opt-in requiredClaims option can block missing claims, and signature verification itself is not bypassed. This issue is fixed in version 6.3.0.
CVSS:3.1/AV:N/AC:L/PR:L/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/86e83efd8b5244f50859532d99244f0a9a9a4368 security-advisories@github.com
- https://github.com/nearform/fast-jwt/pull/639 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-5hjw-83fp-phq9 security-advisories@github.com
- https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9 134c704f-9b21-4f2e-91b3-4a467353bcc0