Heap-based buffer overflow in the Certificate Trust List (CTL) Provider service (CTLProvider.exe) in Cisco Unified Communications Manager (CUCM) 4.2 before 4.2(3)SR3 and 4.3 before 4.3(1)SR1, and CallManager 4.0 and 4.1 before 4.1(3)SR5c, allows remote attackers to cause a denial of service or execute arbitrary code via a long request.