Unspecified vulnerability in Cisco Adaptive Security Appliances (ASA) 5500 Series and PIX Security Appliances 7.0 before 7.0(8)3, 7.1 before 7.1(2)78, 7.2 before 7.2(4)16, 8.0 before 8.0(4)6, and 8.1 before 8.1(1)13, when configured as a VPN using Microsoft Windows NT Domain authentication, allows remote attackers to bypass VPN authentication via unknown vectors.