The Packet Data Network Gateway (aka PGW) component on Cisco ASR 5000 devices with software 15.0(912), 15.0(935), and 15.0(938) allows remote attackers to cause a denial of service (Session Manager outage) via malformed fields in an IP packet, aka Bug ID CSCut38476.
http://www.securitytracker.com/id/1032928
http://tools.cisco.com/security/center/viewAlert.x?alertId=39907