The GN4 Publishing System before version 2.6 contains an IDOR vulnerability in its API endpoints that handle user objects. Authenticated users can manipulate user ID parameters to access sensitive data of other users, such as encrypted passwords and recovery information (security questions and answers). This flaw constitutes an authorization bypass (CWE-639) and can lead to account compromise. The CVSS 4.0 base score is 8.6, indicating a high-severity network vulnerability exploitable without user interaction but requiring low privileges.

An attacker with valid authentication can retrieve sensitive account information of arbitrary users, including encrypted passwords and security recovery data. This can facilitate account takeover or unauthorized access to user accounts within the GN4 Publishing System. The vulnerability compromises confidentiality and integrity of user credentials and recovery mechanisms.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict API access to trusted users only and monitor for unusual API requests involving user ID parameters. Avoid exposing sensitive account data in API responses. Follow vendor updates closely for an official patch or mitigation instructions.