Engelsystem is a shift planning system for chaos events. If a users' password is compromised and an attacker gained access to a users' account, i.e., logged in and obtained a session, an attackers' session is not terminated if the users' account password is reset. This vulnerability has been fixed in the commit `dbb089315ff3d`. Users are advised to update their installations. There are no known workarounds for this vulnerability.
According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."