Revision Note: V1.2 (January 11, 2011): Added the workaround, Prevent the recursive loading of CSS style sheets in Internet Explorer, and revised Executive Summary to reflect investigation of limited attacks. Advisory Summary:Microsoft is investigating new, public reports of targeted attacks attempting to exploit a vulnerability in all supported versions of Internet Explorer. The main impact of the vulnerability is remote code execution. This advisory contains workarounds and mitigations for this issue.