The \'crowd-application\' plugin module (notably used by the Google Apps plugin) in Atlassian Crowd from version 1.5.0 before version 3.1.2 allowed an attacker to impersonate a Crowd user in REST requests by being able to authenticate to a directory bound to an application using the feature. Given the following situation: the Crowd application is bound to directory 1 and has a user called admin and the Google Apps application is bound to directory 2, which also has a user called admin, it was possible to authenticate REST requests using the credentials of the user coming from directory 2 and impersonate the user from directory 1.