CVE-2026-34950
Critical
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.
SeverityCritical
CVSS9.1
Exploit probability—
ProductNearform Fast-jwt
PublishedApr 6, 2026
First seenApr 6, 2026
Weakness typeCWE-327CWE-327
How to fix
Update
- nearform fast-jwt6.2.0 or later
- fast-jwt6.2.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| nearform fast-jwt | v < 6.2.0 | 6.2.0 |
| fast-jwtnpm | v < 6.2.0 | 6.2.0 |
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