Not Failing Securely ('Failing Open') Affecting fast-jwt package, versions *
Threat Intelligence
Exploit Maturity
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
Proof of Concept
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Test your applications- Snyk IDSNYK-JS-FASTJWT-15907854
- published5 Apr 2026
- disclosed3 Apr 2026
- creditdmbs335
Introduced: 3 Apr 2026
NewCVE-2026-35042 (opens in a new tab)Common Vulnerabilities and Exposures (CVE) are common identifiers for publicly known security vulnerabilities
Common Weakness Enumeration (CWE) is a category system for software weaknesses
How to fix?
There is no fixed version for fast-jwt.
Overview
fast-jwt is a Fast JSON Web Token implementation
Affected versions of this package are vulnerable to Not Failing Securely ('Failing Open') due to improper validation of the crit header parameter. An attacker can bypass intended authorization policies by crafting a signed token with unknown critical header parameters, which are improperly accepted and processed.