Cisco Unified Communications Manager (CUCM) with software 6.x and 7.x before 7.1(5b)su5, 8.0 before 8.0(3a)su3, and 8.5 and 8.6 before 8.6(2a)su1 and Cisco Business Edition 3000 with software before 8.6.3 and 5000 and 6000 with software before 8.6(2a)su1 allow remote attackers to cause a denial of service (device reload) via a crafted SCCP registration, aka Bug ID CSCtu73538.