The Secure Channel (aka SChannel) security package in Microsoft Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7, when IIS 7.x is used, does not properly process client certificates during SSL and TLS handshakes, which allows remote attackers to cause a denial of service (LSASS outage and reboot) via a crafted packet, aka "TLSv1 Denial of Service Vulnerability."