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."