Request Tracker (RT) 4.x before 4.0.13 does not properly enforce the DeleteTicket and "custom lifecycle transition" permission, which allows remote authenticated users with the ModifyTicket permission to delete tickets via unspecified vectors.
http://secunia.com/advisories/53522
http://lists.bestpractical.com/pipermail/rt-announce/2013-May/000227.html
http://lists.bestpractical.com/pipermail/rt-announce/2013-May/000226.html