The Protocol Independent Multicast (PIM) application in Cisco Adaptive Security Appliance (ASA) Software 9.2(0.0), 9.2(0.104), 9.2(3.1), 9.2(3.4), 9.3(1.105), 9.3(2.100), 9.4(0.115), 100.13(0.21), 100.13(20.3), 100.13(21.9), and 100.14(1.1) does not properly implement multicast-forwarding registration, which allows remote attackers to cause a denial of service (forwarding outage) via a crafted multicast packet, aka Bug ID CSCus74398.