Microsoft has released Security Advisory 979352 to alert users of a vulnerability in Microsoft Internet Explorer. The advisory indicates that exploitation of this vulnerability may allow an attacker to execute arbitrary code. Microsoft also indicates that it is aware of public, active exploitation of this vulnerability.
US-CERT encourages users and administrators to review Microsoft Security Advisory 979352 and apply the suggested workaround of setting the Internet zone security setting to High to help mitigate the risks.
Additional information about this vulnerability can be found in Vulnerability Note VU#492515.