Sep 21, 2012 Serious Zero Day Security Vulnerability in Internet Explorer A Zero Day vulnerability means that this vulnerability was previously unknown and is being actively exploited. This security vulnerability could allow remote control of your computer. It is important that your automatic updates are enabled. Refer to the Microsoft Security Bulletin for more information. As a general rule, Chrome and Firefox are more secure browsers and should be used particularly for general browsing of the Internet. Continue to use Internet Explorer for accessing systems on campus that require Internet Explorer.