fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.4, the fast-jwt createVerifier cache can continue accepting a previously valid, signed JWT after its exp time when caching is enabled and the token has exp but no iat. In src/verifier.js, cacheSet derives the exp cache deadline only when iat is present, so the cache falls back to cacheTTL, and a later cache hit returns the saved payload before verifyToken rechecks expiration. An attacker who can replay the same cached bearer token can extend access until the cache entry expires, but cannot forge a token through this issue. This issue is fixed in version 6.3.4.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-x937-hj6v-793p fast-jwt: Verifier cache accepts expired JWTs without iat.
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

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 6.3.4, the fast-jwt createVerifier cache can continue accepting a previously valid, signed JWT after its exp time when caching is enabled and the token has exp but no iat. In src/verifier.js, cacheSet derives the exp cache deadline only when iat is present, so the cache falls back to cacheTTL, and a later cache hit returns the saved payload before verifyToken rechecks expiration. An attacker who can replay the same cached bearer token can extend access until the cache entry expires, but cannot forge a token through this issue. This issue is fixed in version 6.3.4.
Title fast-jwt: Verifier cache accepts expired JWTs without iat.
Weaknesses CWE-613
References
Metrics cvssV3_1

{'score': 4.2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-08T21:41:55.342Z

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

Link: CVE-2026-107719

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-08T22:17:27.913

Modified: 2026-10-08T22:17:28.053

Link: CVE-2026-107719

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses