WBCE CMS is Vulnerable to Privilege Escalation via Group ID Manipulation (IDOR)

WBCE CMS is a content management system. Prior to version 1.6.4, a low-privileged user in WBCE CMS can escalate their privileges to the Administrators group by manipulating the groups[] parameter in the /admin/users/save.php request. The UI restricts users to assigning only their existing group, but server-side validation is missing, allowing attackers to overwrite their group membership and obtain full administrative access. This results in a complete compromise of the CMS. This issue has been patched in version 1.6.4.