Cisco Unified Communications Manager (aka CUCM, formerly CallManager) 5.x before 5.1(3g), 6.x before 6.1(4), 7.0.x before 7.0(2a)su1, and 7.1.x before 7.1(2) allows remote attackers to cause a denial of service (service restart) via malformed SIP messages, aka Bug ID CSCsz95423.