All versions of Internet Explorer except version 5 on Windows 2000 are vulnerable to a previously unknown, unpatched vulnerability in Adobe’s Acrobat and Reader softwares.

The Protected Mode in IE7 and IE8 “limits the impact of this vulnerability” if the user is using Windows Vista or 7. Otherwise,
the exploit code runs with the same privileges as the user.

Windows Server 2003 and 2008 users have limited impacts due to Enhanced Security Configuration.

According to Microsoft, it is aware of “limited, active attacks attempting to use this vulnerability against Internet Explorer 6.”

Source: PCMAG