CVE-2026-75509
Published:August 24, 2026
Updated:September 24, 2026
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.
Affected Packages
joserfc (CONDA):
Affected version(s) >=0.9.0 <1.7.3Fix Suggestion:
Update to version 1.7.3https://github.com/authlib/joserfc.git (GITHUB):
Affected version(s) >=0.2.0 <1.7.3Fix Suggestion:
Update to version 1.7.3joserfc (PYTHON):
Affected version(s) >=0.1.0 <1.7.3Fix Suggestion:
Update to version 1.7.3Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
EPSS
Base Score:
0.09