CVE catalog

CVE-2026-35040

fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.1, using certain modifiers on RegExp objects in the allowedAud, allowedIss, allowedSub, allowedJti, or allowedNonce options in

[CVE catalog]

Severity
Medium · CVSS 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Published
Source
[NVD] · [CVE record]
EPSS
0.38% · Oct 25, 2026

fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.1, using certain modifiers on RegExp objects in the allowedAud, allowedIss, allowedSub, allowedJti, or allowedNonce options in verify functions can cause certain unintended behaviours. This is because some modifiers are stateful and will cause failures in every second verification attempt regardless of the validity of the token provided. Such modifiers are /g (global matching) and /y (sticky matching). This does NOT allow invalid tokens to be accepted, only for valid tokens to be improperly rejected in some configurations. Instead it causes 50% of valid authentication requests to fail in an alternating pattern. This vulnerability is fixed in 6.2.1.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

DistributionPackageReleaseVersionStatus
Cpefast-jwtNot reported6.2.1fixed
Cpefast-jwtNot reported6.2.1fixed

Fixed-version evidence

DistributionPackageTypeReleaseFixed versionUrgencyOriginBugs
Cpefast-jwtcpeNot reported6.2.1Not reportedNot reportedNot reported
Cpefast-jwtcpeNot reported6.2.1Not reportedNVD-CVE-2026-35040Not reported

OpenFactory catalog packages

No matching packages in this catalog.

Observed:

References

[FIRST EPSS] · [National Vulnerability Database (NVD)]