CVE-2026-75509
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.
- Published Aug 24, 2026
- CVSS 6.5 medium
- 0.1% chance of exploitation in the next 30 days (EPSS)
- A fix is available
Affected software
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