According to Rosenblatt, the warning issued by the US and UK governments, affects all major versions of the browser from the past decade. The unpatched flaw, they say, "allows attackers to install malware on your computer that could be used to steal personal data, track online behavior or even gain control of the computer." The bug, a known Flash-based exploit technique to attack financial and defense organizations in the US, was discovered by FireEye.
In a statement, Microsoft told CNET, "On April 26, 2014, Microsoft released Security Advisory 2963983 to notify customers of a vulnerability in Internet Explorer. At this time we are aware of limited, targeted attacks. We encourage customers to follow the suggested mitigations outlined in the security advisory while an update is finalized."