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CVE-2026-35041

MEDIUM

4.2

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.

CVE Details

CVSS v3.1 Score4.2

SeverityMEDIUM

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

Attack VectorNETWORK

ComplexityHIGH

Privileges RequiredHIGH

User InteractionREQUIRED

Published4/9/2026

Last Modified4/14/2026

Sourcenvd

Honeypot Sightings0

Affected Products

nearform:fast-jwt

Weaknesses (CWE)

CWE-1333

References

https://github.com/nearform/fast-jwt/commit/b0be0ca161593836a153d5180ca5358ad9b5de94(security-advisories@github.com)

https://github.com/nearform/fast-jwt/pull/595(security-advisories@github.com)

https://github.com/nearform/fast-jwt/releases/tag/v6.2.1(security-advisories@github.com)

https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf(security-advisories@github.com)

https://github.com/nearform/fast-jwt/security/advisories/GHSA-cjw9-ghj4-fwxf(134c704f-9b21-4f2e-91b3-4a467353bcc0)

IOC Correlations

No correlations recorded

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