CVE-2026-30927 Admidio: Event participation IDOR - non-leaders can register other users for events via user_uuid parameter

Admidio is an open-source user management solution. Prior to 5.0.6, in modules/events/eventsfunction.php, the event participation logic allows any user who can participate in an event to register OTHER users by manipulating the useruuid GET parameter. The condition uses || OR, meaning if...