A new exploit for IE9 bypasses all security measures in even the latest fully patched version of Windows 7, according to a French security company. The exploit uses an unpatched zero-day vulnerability in Internet Explorer 9. The vulnerability is also present in IE8, 7 and 6, which Vupen has not made a working exploit. The risk of this exploit so far is limited: exploit code has not been spotted in the wild. IE9 has a market share of 3.6 percent amongst Windows 7 users, but only 1.04 percent.
Source: https://thehackernews.com/2011/04/ie9-exploit-puts-windows-7-sp1-at-risk.html