The Windows kernel-mode drivers in win32k.sys in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista SP1 and SP2, and Server 2008 Gold and SP2 "do not properly validate changes in certain kernel objects," which allows local users to execute arbitrary code via vectors related to Device Contexts (DC) and the GetDCEx function, aka "Win32k Improper Data Validation Vulnerability."