Windows Text Services (WTS) in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows remote attackers to execute arbitrary code via a crafted (1) web site or (2) file, aka "WTS Remote Code Execution Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-020