Best Practical Solutions RT 3.x before 3.8.12 and 4.x before 4.0.6 does not properly disable groups, which allows remote authenticated users to bypass intended access restrictions in opportunistic circumstances by leveraging a group membership.
http://www.securityfocus.com/bid/53660
http://secunia.com/advisories/49259
http://lists.bestpractical.com/pipermail/rt-announce/2012-May/000204.html
http://lists.bestpractical.com/pipermail/rt-announce/2012-May/000203.html
http://lists.bestpractical.com/pipermail/rt-announce/2012-May/000202.html