CVE-2026-34950

critical · 9.1

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.

9.1

CVSS

0.2%

EPSS (exploit prob.)

15th

EPSS percentile

2026-04-06

Published

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

Weaknesses

CWE-327

Affected products

Vendor	Product	Affected versions
nearform	fast-jwt	< 6.2.0

Check a specific version with /api/v1/cve/match.

References

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

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-34950