Cisco IOS 15.3 and 15.4, Cisco IOS XE 3.8 through 3.11, and Cisco Unified Communications Manager allow remote attackers to cause a denial of service (device reload) via malformed SIP messages, aka Bug ID CSCuj23293.
http://www.securitytracker.com/id/1035421
http://www.securitytracker.com/id/1035420
http://www.securityfocus.com/bid/85372
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160323-sip