Cisco Adaptive Security Appliances (ASA) 5500 series devices with software 7.2 through 8.4 do not properly perform proxy authentication during attempts to cut through a firewall, which allows remote attackers to obtain sensitive information via a connection attempt, aka Bug ID CSCtx42746.
http://www.securitytracker.com/id?1027008
http://www.securityfocus.com/bid/53558
http://www.cisco.com/web/software/280775065/89203/ASA-843-Interim-Release-Notes.html