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.
Published: 2026-10-08
Score: 5.9 Medium
EPSS: n/a
KEV: No
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Remediation

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-687g-22h4-j4w4 fast-jwt clockTolerance: Infinity silently bypasses both exp and nbf validation (and persists in the verifier cache)
History

Thu, 08 Oct 2026 22:00:00 +0000

Type Values Removed Values Added
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.
Title fast-jwt clockTolerance: Infinity silently bypasses both exp and nbf validation (and persists in the verifier cache)
Weaknesses CWE-613
CWE-682
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-08T21:45:57.545Z

Reserved: 2026-10-08T17:21:52.975Z

Link: CVE-2026-107721

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-08T22:17:28.263

Modified: 2026-10-08T22:17:28.410

Link: CVE-2026-107721

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-613

    Insufficient Session Expiration

  • CWE-682

    Incorrect Calculation