Improper Authentication Affecting fast-jwt package, versions <6.2.4
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
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Test your applications- Snyk IDSNYK-JS-FASTJWT-16439016
- published7 May 2026
- disclosed6 May 2026
- creditbhaswanthc
Introduced: 6 May 2026
NewCVE-2026-44351 (opens in a new tab)How to fix?
Upgrade fast-jwt to version 6.2.4 or higher.
Overview
fast-jwt is a Fast JSON Web Token implementation
Affected versions of this package are vulnerable to Improper Authentication in the async key resolver when it returns an empty string or zero-length buffer. An attacker can gain unauthorized access and assume arbitrary identities by forging JWTs signed with an empty secret, which are then accepted as valid tokens.
Note: This is only exploitable if the application uses an asynchronous callback for key resolution and the callback can return an empty string or zero-length buffer, while HMAC algorithms are allowed (default configuration).