The Certificate Authority Proxy Function (CAPF) service in Cisco Unified Communications Manager (CUCM) 4.1 before 4.1(3)SR7, 4.2 before 4.2(3)SR4, and 4.3 before 4.3(2) allows remote attackers to cause a denial of service (service crash) via malformed network traffic, aka Bug ID CSCsk46770.