WASHINGTON DC – It’s not often that the US government weighs in on the browser wars, but a new Internet Explorer vulnerability that affects all major versions of the browser from the past decade has forced it to raise an alarm: Stop using IE.

This zero-day exploit is an unpatched flaw in the Microsoft browser that allows attackers to run malicious code remotely, CNET News.Com reported. Security firm FireEye said that it is currently being used to attack financial and defense organizations in the US via Internet Explorer 9, 10, and 11. Those versions of the browser run on Windows Vista, Windows 7, and Windows 8, although the exploit is present in Internet Explorer 6 and above.

While the Department of Homeland Security’s Computer Emergency Readiness Team regularly issues browser advisories, this is one of the few times that the CERT team has recommended that people avoid using a specific browser.

FireEye recommends that if you can’t switch browsers, that you disable Internet Explorer’s Flash plug-in. You can also use IE with Microsoft’s Enhanced Mitigation Experience Toolkit security app, but that will not be as secure as simply switching browsers.

Microsoft and the Department of Homeland Security did not immediately respond to requests for comment.

Statistics vary as to how many people actually use Internet Explorer. NetMarketShare puts the total at around 55 percent of the desktop browser market, while competitor StatCounter says that 22.58 percent of people use IE. While the disparity is large, in either case the flaw affects a huge number of browsers being actively used.