In Open Ticket Request System (OTRS) 3.3.x through 3.3.16, 4.x through 4.0.23, and 5.x through 5.0.19, an attacker with agent permission is capable of opening a specific URL in a browser to gain administrative privileges / full access. Afterward, all system settings can be read and changed. The URLs in question contain index.pl?Action=Installer with ;Subaction=Intro or ;Subaction=Start or ;Subaction=System appended at the end.