Description
fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts Infinity for clockTolerance because its option validation checks type and negativity but not finiteness. In validateClaimDateValue, infinite positive and negative modifiers make exp and nbf comparisons always pass, allowing expired or not-yet-active tokens to be accepted. The verifier cache also derives infinite bounds, so entries created under this configuration can remain valid until eviction. Exploitation requires an application administrator or equivalent configuration path to set clockTolerance to Infinity. This issue is fixed in version 6.3.0.
Related CPE's
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References
CVSS impact metrics
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
5.9 · Medium
Information
Source identifier
Vulnerability status
Deferred
Published
2026-10-08T22:17:28.263Z
10 hours agoLast modified
2026-10-08T22:17:28.410Z
10 hours ago