Microsoft released a new critical patch for the Windows Meta File vulnerability in Internet Explorer. This security update replaces the previous WMF patch.WMF Image Parsing Memory Corruption Vulnerability
When Internet Explorer displays a Web page that contains a specially crafted WMF image, Windows system memory may be corrupted in such a way that an attacker could execute arbitrary code and cause a denial of service (crash).
Download Microsoft WMF Patch
Microsoft rates as "critical" any security threat that could allow a malicious Internet worm to spread without any action required on the part of the user.