win32k.sys in the kernel-mode drivers in Microsoft Windows 7 SP1 and Server 2008 R2 SP1 does not properly consider thread-owned objects during the processing of window handles, which allows local users to gain privileges via a crafted application, aka "Win32k Window Handle Vulnerability."
http://www.securityfocus.com/bid/64725
http://www.securitytracker.com/id/1029600
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-003