critical9.1
CVE-2026-34950
fast-jwt: Incomplete fix for CVE-2023-48223: JWT Algorithm Confusion via Whitespace-Prefixed RSA Public Key
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | fast-jwt | <= 6.1.0 | 6.2.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nearform | Fast-Jwt | before 6.2.0 |