The flaw, which affects Internet Explorer versions six and up, allows hackers to gain complete access to a PC.
The U.S. Department of Homeland Security, who normally does not make announcements regarding computer software, issued a warning to users on Monday.
Homeland Security recommends that users or administrators "enable Microsoft EMET where possible" and "consider employing an alternative web browser until an official update is available."
EMET (Enhanced Mitigation Experience Toolkit) will protect you and let you browse the web without altering your experience.
Microsoft should release a patch to fix the bug soon, either in the company's next "Patch Tuesday" update (May 13) or in an off-schedule patch specifically for this issue. It's unclear if Windows XP will get the patch.
In the mean time, try using other web-browsers such as Google Chrome and Mozilla Firefox.
Read more on the security issue on Mashable.
Copyright 2016 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.