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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-35040 Detail

Description

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/nearform/fast-jwt/commit/18d25904e4617e8753526d1b3ab5a2cccdea726a GitHub, Inc.
https://github.com/nearform/fast-jwt/pull/593 GitHub, Inc.
https://github.com/nearform/fast-jwt/releases/tag/v6.2.1 GitHub, Inc.
https://github.com/nearform/fast-jwt/security/advisories/GHSA-3j8v-cgw4-2g6q GitHub, Inc.

Weakness Enumeration

CWE-ID CWE Name Source
CWE-440 Expected Behavior Violation GitHub, Inc.  
CWE-697 Incorrect Comparison GitHub, Inc.  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-35040
NVD Published Date:
04/09/2026
NVD Last Modified:
04/09/2026
Source:
GitHub, Inc.