CVE-2026-34950
fast-jwt has an incomplete fix for CVE-2023-48223: JWT Algorithm Confusion via Whitespace-Prefixed RSA Public Key
- State
- Published
- Severity
- 9.1 Critical
- Published
- Apr 6, 2026
- Updated
- Apr 6, 2026
- Reserved
- Mar 31, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | GitHub_M |
Weaknesses
- CWE-327 Use of a Broken or Risky Cryptographic Algorithm
Affected Products
| Product | Versions |
|---|---|
fast-jwtnearform |
|
References
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