The Unicast Reverse Path Forwarding (uRPF) implementation in Cisco Adaptive Security Appliance (ASA) Software 9.3(1.50), 9.3(2.100), 9.3(3), and 9.4(1) mishandles cases where an IP address belongs to an internal interface but is also in the ASA routing table, which allows remote attackers to bypass uRPF validation via spoofed packets, aka Bug ID CSCuv60724.