Win32k.sys in the kernel-mode drivers in Microsoft Windows Server 2003 SP2, Vista SP2, and Server 2008 SP2 allows local users to gain privileges via a crafted application, as exploited in the wild in April 2015, aka "Win32k Elevation of Privilege Vulnerability."
https://www.fireeye.com/blog/threat-research/2015/04/probable_apt28_useo.html
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-051