Microsoft issued a Security Advisory on April 26, 2014 relating to a vulnerability in Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, Internet Explorer 10, and Internet Explorer 11 for the majority of current Windows Operating Systems including: Vista, Windows 7, Windows 8, Windows 8.1, Windows 2003 Server, Windows 2008 Server, Windows 2012 Server, Windows RT, Windows RT 8.1.
"The vulnerability may corrupt memory in a way that allow an attacker to execute code" under the active user account. Full details of the advisory can be found by reviewing Microsoft Security Advisory 2963983, along with suggested actions to reduce the risk whilst Microsoft continues their investigation and remediation efforts.
Excalibur Thoughts:
Security Vulnerabilities are discovered in applications from time-to-time, and Microsoft is usually pretty quick to re-mediate them, however If you use Internet Explorer as your primary browser, now may be a good time to look at the alternatives.
Google Chrome, Mozilla Firefox and Opera all provide a comparable, experience to Internet Explorer. If you're generally happy with Internet Explorer, and don't want to make a permanent switch, then make sure you follow the suggested actions from Microsoft, in their security advisory. However our recommendation is that, at least in the short term until the vulnerability has been patched, you consider making a transition to another browser.