The DHCPv6 relay implementation in Cisco Adaptive Security Appliance (ASA) software 9.0 before 9.0(4.37), 9.1 before 9.1(6.6), 9.2 before 9.2(4), 9.3 before 9.3(3.5), and 9.4 before 9.4(2) allows remote attackers to cause a denial of service (device reload) via crafted DHCPv6 packets, aka Bug IDs CSCus56252 and CSCus57142.