Red Hat JBoss Enterprise Application Platform (EAP) before 6.1.0 and JBoss Portal before 6.1.0 does not load the implementation of a custom authorization module for a new application when an implementation is already loaded and the modules share class names, which allows local users to control certain applications' authorization decisions via a crafted application.
http://rhn.redhat.com/errata/RHSA-2013-1437.html