Cisco Adaptive Security Appliances (ASA) 5500 series devices with software 7.0 before 7.0(8.12), 7.1 and 7.2 before 7.2(5.2), 8.0 before 8.0(5.21), 8.1 before 8.1(2.49), 8.2 before 8.2(3.6), and 8.3 before 8.3(2.7) and Cisco PIX Security Appliances 500 series devices, when transparent firewall mode is configured but IPv6 is not configured, allow remote attackers to cause a denial of service (packet buffer exhaustion and device outage) via IPv6 traffic, aka Bug ID CSCtj04707.