The is because it can be exploited by creating a malicious website that attacks visitors who use a vulnerable browser. Those browsers include IE6, IE7, IE8 and IE9. The only version not affected is IE10.

The one-click fix will protect computers immediately, Yunsun Wee, director of Microsoft's Trustworthy Computing group. On Friday, Microsoft will diverge from its normal patch schedule and issue a "cumulative update" for IE through its Windows Update service.

The cumulative update is named MS12-063 and will be released around 10 a.m. Pacific Time on Friday. It will also address four other critical, remote code execution vulnerabilities, Wee wrote.

"We recommend that you install this update as soon as it is available," Wee wrote. "If you have automatic updates enabled on your PC, you won't need to take any action -- it will automatically be updated on your machine. This will not only reinforce the issue that the Fix It addressed, but cover other issues as well."

Microsoft will hold a at 12 p.m. Pacific Time on Friday to answer questions.