Vulnerability in Nearform Fast-Jwt
CVE-2026-107722
fast-jwt provides fast JSON Web Token (JWT) implementation. From 6.2.0 until 6.3.0, fast-jwt can misclassify RSA public-key text as an HMAC secret when the key has non-whitespace content before its PEM header. In src/crypto.js, performDetectPublicKeyAlgorithms trims whitespace but publicKeyPemMatcher remains start-anchored, so comments, control characters, zero-width characters, or wrapper text can prevent PEM detection and reach the HMAC fallback. An attacker who knows the public key bytes can sign arbitrary HS256 claims with that public material when HS256 is inferred or allowed, resulting in authentication or authorization bypass. An asymmetric-only algorithm allowlist prevents the attack. This issue is fixed in version 6.3.0.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Nearform Fast-Jwt — versions >= 6.2.0, < 6.3.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-107722?
- CVE-2026-107722 is a critical-severity vulnerability in Nearform Fast-Jwt, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2026-10-08.
- How severe is CVE-2026-107722?
- Critical severity. CVSS v3 base score is 9.8 out of 10.