Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allow remote attackers to cause a denial of service (daemon hang) via a web-service request containing a crafted X.509 certificate that is not properly handled during validation, aka "Digital Signatures Vulnerability."