Microsoft has received reports of "a small number of targeted attacks" based on a vulnerability in Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9. Internet Explorer 10 is not affected. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability.
Throughout its history Internet Explorer has been subjected to many security vulnerabilities and concerns: Much of the spyware, adware, and computer viruses across the Internet are made possible by exploitable bugs and flaws in the security architecture of Internet Explorer, sometimes requiring nothing more than viewing of a malicious web page in order to install themselves. This is known as a "drive-by install". There are also attempts to trick the user into installing malicious software by misrepresenting the software's true purpose in the description section of an ActiveX security alert.