fast-jwt: Verifier cache accepts expired JWTs without iat.

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-107719
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-08 22:17:27 UTC
Updated2026-10-09 16:17:23 UTC
Descriptionfast-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.

Risk And Classification

Primary CVSS: v3.1 4.2 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS: 0.002260000 probability, percentile 0.122790000 (date 2026-10-11)

Problem Types: CWE-613 | CWE-613 CWE-613: Insufficient Session Expiration

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.2MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
3.1CNADECLARED4.2MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Nearform Fast-jwt affected < 6.3.4 Not specified

References

ReferenceSourceLinkTags
github.com/nearform/fast-jwt/releases/tag/v6.3.4 [email protected] github.com
github.com/nearform/fast-jwt/commit/fc1ddbbe5ce38066ba2cea0b0ce023393275... [email protected] github.com
github.com/nearform/fast-jwt/security/advisories/GHSA-x937-hj6v-793p 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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