fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass vulnerability in fast-jwt's async key-resolver flow allows any unauthenticated attacker to forge arbitrary JWTs that are accepted as authentic. When the application's key resolver returns an empty string (''), for example via the common keys[decoded.header.kid] || '' JWKS-style fallback, fast-jwt converts it to a zero-length Buffer, hands it to crypto.createSecretKey, derives allowedAlgorithms = ['HS256','HS384','HS512'] from it, and then verifies the token's signature against an empty-key HMAC. The attacker simply computes HMAC-SHA256(key='', input='${header}.${payload}'), which Node accepts without complaint — and the verifier returns the attacker-chosen payload (sub, admin, scopes, etc.) as authentic. This vulnerability is fixed in 6.2.4.
References
Configurations
No configuration.
History
14 May 2026, 19:16
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://github.com/nearform/fast-jwt/security/advisories/GHSA-gmvf-9v4p-v8jc - |
13 May 2026, 20:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-13 20:16
Updated : 2026-05-14 19:16
NVD link : CVE-2026-44351
Mitre link : CVE-2026-44351
CVE.ORG link : CVE-2026-44351
JSON object : View
Products Affected
No product.