CVE-2026-34950

CRITICAL

9.1

Description

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patched.

CVE Details

CVSS v3.1 Score9.1

SeverityCRITICAL

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

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published4/6/2026

Last Modified4/7/2026

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-327

References

https://github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm-w987(security-advisories@github.com)

IOC Correlations

No correlations recorded

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