For a week now it has been known that there is an IE9 Zero Day Vulnerability.
Get This Zero Day Vulnerability Fixed
Now Microsoft have published a fix which came to me today in the form of an update as follows (for Windows 7):
Cumulative Security Update for Internet Explorer 9 for Windows 7 for x64-based Systems (KB2744842)
Update type: Important
Security issues have been identified that could allow an attacker to compromise a system that is running Microsoft Internet Explorer and gain control over it. You can help protect your system by installing this update from Microsoft. After you install the update, you may have to restart your computer.
More information: http://go.microsoft.com/fwlink/?LinkId=255505
Help and Support: http://support.microsoft.com
Zero Day Vulnerabilities are those which have already been exploited by the time the software developer finds out about them.