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 browser that allows attackers to run malicious code remotely. 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.