Internet Explorer 7 and Firefox 2.0 share a logic flaw. The issue is actually more severe, as the two versions of the Microsoft and Mozilla browsers are not the only ones affected. In this regard, the vulnerability impacts Internet Explorer 5.01, Internet Explorer 6 and Internet Explorer 7 but also Firefox 1.5.0.9. Microsoft has stressed the fact that IE7 on Windows Vista is not affected in any manner.
Yet another reason to move to Vista? Hah! This seems like a rather serious exploit, which hopefully will be fixed sooner than later.
Source: Softpedia