win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 does not properly validate user-mode input, which allows local users to gain privileges via a crafted application, aka "Win32k Improper User Input Validation Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12070
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-012
http://www.vupen.com/english/advisories/2011/0325
http://www.securityfocus.com/bid/46141