The General Packet Radio Switching Tunneling Protocol 1 (aka GTPv1) implementation on Cisco ASR 5000 Packet Data Network Gateway devices before 19.4 allows remote attackers to cause a denial of service (Session Manager process restart) via a crafted GTPv1 packet, aka Bug ID CSCuz46198.
http://www.securitytracker.com/id/1036152
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160621-asr