The Windows Metafile vulnerability—also called the Metafile Image Code Execution and abbreviated MICE—is a security vulnerability in the way some versions of the Microsoft Windows operating system handled images in the Windows Metafile format. It permits arbitrary code to be executed on affected computers without the permission of their users. It was discovered on December 27, 2006, and the first reports of affected computers were announced within 24 hours. Microsoft released a high-priority update to eliminate this vulnerability via Windows Update on January 5, 2007. Attacks using this vulnerability are known as WMF exploits.