Also left vulnerable to attack is Microsoft Visual Studio, a program used to develop websites and other online utilities.
Software engineers around the net pointed out the problem, which involves one faulty component in IE that happens to interact with many important third-party products, such as Flash, leaving them vulnerable to attack.
Apparently the vulnerability is connected to Microsoft's Video ActiveX Control, and specifically linked to a file called msvidctl.dll.
The eighth version of Microsoft Internet Explorer was touted as a major improvement over earlier versions, but after the browser's launch last year, the Redmond, Wash.-based company has had to content with one high-profile security breach after another.
Last December, Microsoft issued an emergency security patch to fix an unrelated problem that left IE vulnerable to attack on certain booby-trapped websites.
In addition, critics have slammed IE for its slowness, cluttered interface and lack of compatibility with a large number of websites.