CVE-2026-35041 | THREATINT

Description

fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is attacker-controlled and the library evaluates it against the supplied RegExp, a crafted JWT can trigger catastrophic backtracking in the JavaScript regex engine, resulting in significant CPU consumption during verification. This vulnerability is fixed in 6.2.1.

PUBLISHED Reserved 2026-03-31 | Published 2026-04-09 | Updated 2026-04-09 | Assigner GitHub_M

MEDIUM: 4.2CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:H

Problem types

CWE-1333: Inefficient Regular Expression Complexity

Product status

>= 5.0.0, < 6.2.1

affected

References

github.com/...st-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf exploit

github.com/...st-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf

github.com/nearform/fast-jwt/pull/595

github.com/...ommit/b0be0ca161593836a153d5180ca5358ad9b5de94

github.com/nearform/fast-jwt/releases/tag/v6.2.1

cve.org (CVE-2026-35041)

nvd.nist.gov (CVE-2026-35041)

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