The failover ipsec implementation in Cisco Adaptive Security Appliance (ASA) Software 9.1 before 9.1(6), 9.2 before 9.2(3.3), and 9.3 before 9.3(3) does not properly validate failover communication messages, which allows remote attackers to reconfigure an ASA device, and consequently obtain administrative control, by sending crafted UDP packets over the local network to the failover interface, aka Bug ID CSCur21069.