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 do not properly manage a window class, which allows local users to gain privileges by creating a window, then using (1) the SetWindowLongPtr function to modify the popup menu structure, or (2) the SwitchWndProc function with a switch window information pointer, which is not re-initialized when a WM_NCCREATE message is processed, aka "Win32k Window Class Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12085
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2010/ms10-073
http://www.us-cert.gov/cas/techalerts/TA10-285A.html
http://www.exploit-db.com/exploits/15894
http://mista.nu/blog/2010/12/01/windows-class-handling-gone-wrong/