Medium 5.3Published Apr 9, 2026

CVE-2026-35040fast-jwt provides fast JSON Web Token (JWT) implementation.

Updated under an hour ago (2026-10-19 06:25 UTC)

Does this affect you?

It affects nearform fast-jwt. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for nearform fast-jwt

Exploited in the last 30 days

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.

CVSS: 5.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE): CWE-440, CWE-697
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Jun 17, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nearform fast-jwt nearform:fast-jwt	before 6.2.1	NVD

References

https://github.com/nearform/fast-jwt/commit/18d25904e4617e8753526d1b3ab5a2cccdea726apatch
https://github.com/nearform/fast-jwt/pull/593issue-tracking, patch
https://github.com/nearform/fast-jwt/releases/tag/v6.2.1product, release-notes
https://github.com/nearform/fast-jwt/security/advisories/GHSA-3j8v-cgw4-2g6qexploit, mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.