Critical severity9.1NVD Advisory· Published Apr 6, 2026· Updated Apr 22, 2026
CVE-2026-34950
CVE-2026-34950
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.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fast-jwtnpm | < 6.2.0 | 6.2.0 |
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
4- github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm-w987nvdExploitVendor AdvisoryWEB
- github.com/advisories/GHSA-c2ff-88x2-x9pgghsaADVISORY
- github.com/advisories/GHSA-mvf2-f6gm-w987ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-34950ghsaADVISORY
News mentions
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