The June cumulative security update for Internet Explorer 6, 7, 8, 9, and 10 is available on Windows Update. It fixes nineteen vulnerabilities that were reported in time before they were publicly disclosed. The most serious vulnerabilities relate to remote code execution if a user visits an attacker’s website. The user can then gain the same rights as the user.
Users with UAC (User Account Control) enabled are better protected against attacks. The update is on Windows Update, so you don't need to take any special action if you have automatic updates enabled. Otherwise, I recommend deploying this update as soon as possible, because the most vulnerable systems are in the time between the disclosure of the vulnerability and the installation of the security update.
The update is rated critical on Windows client and recommended on Windows Server. Internet Explorer 9 and 10 are not affected because it is not affected by default.
An update to Adobe Flash Player in Internet Explorer 10 for Windows 8 and Windows Server 2012 has also been released, which is also rated as critical.
For more information, see MS13-047 and the KB294871 Support article.