Citrix XenApp (formerly Presentation Server) 4.5 Hotfix Rollup Pack 3 does not apply an access policy when it is defined with the Access Gateway Advanced Edition filters, which allows attackers to bypass intended access restrictions via unknown vectors.
http://www.vupen.com/english/advisories/2009/1154
http://www.securitytracker.com/id?1022114
http://www.securityfocus.com/bid/34691
http://support.citrix.com/article/CTX118792