CVE-2026-107719Medium· 4.2▾ TwilightPoC availablefast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.4, the fast-jwt createVerifier cache can continue accepting a previously valid, signed JWT after its exp time when caching is enabled and the token has exp but no i…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 23.1 · 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
Last analysed / modified upstream
0.2%
Exploit / PoC code exists
0.2% → 0.3%
fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.4, the fast-jwt createVerifier cache can continue accepting a previously valid, signed JWT after its exp time when caching is enabled and the token has exp but no iat. In src/verifier.js, cacheSet derives the exp cache deadline only when iat is present, so the cache falls back to cacheTTL, and a later cache hit returns the saved payload before verifyToken rechecks expiration. An attacker who can replay the same cached bearer token can extend access until the cache entry expires, but cannot forge a token through this issue. This issue is fixed in version 6.3.4.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
fast-jwt <= 6.3.3Patched in:
fast-jwt 6.3.4Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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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-2026-107722Critical· 9.8fast-jwt provides fast JSON Web Token (JWT) implementation
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