CVE-2026-107722Critical· 9.8▾ AbyssalPoC availablefast-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, performDe…
▾ Abyssal zone — Critical with a public exploit or in-the-wild use
impact 53.9 · likelihood 0.1 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Oct 10.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.3%
Last analysed / modified upstream
Exploit / PoC code exists
0.3% → 0.4%
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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
fast-jwt >= 6.2.0, <= 6.2.4Patched in:
fast-jwt 6.3.0Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-107724High· 7.4fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-107723High· 8.1fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-107720High· 7.4fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-107721Medium· 5.9fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-107719Medium· 4.2fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-1529High· 8.1A flaw was found in Keycloak