The Winsock WSAIoctl API in Microsoft Windows Server 2008, as used in ISC BIND 9.6-ESV before 9.6-ESV-R10-P1, 9.8 before 9.8.6-P1, 9.9 before 9.9.4-P1, 9.9.3-S1, 9.9.4-S1, and other products, does not properly support the SIO_GET_INTERFACE_LIST command for netmask 255.255.255.255, which allows remote attackers to bypass intended IP address restrictions by leveraging misinterpretation of this netmask as a 0.0.0.0 netmask.