The October cumulative security update for Internet Explorer 6, 7, 8, 9, 10, and 11 is available on Windows Update. It fixes two publicly known vulnerabilities and eight potentially dangerous 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 for Windows Client and Recommended for Windows Server.
A new version of Adobe Flash Player 11.9 for Internet Explorer 10 and 11 has also been released.
Because Windows 8.1 won't be publicly available until October 18, the Internet Explorer 11 update version is still RTM.
The update includes six additional non-security fixes. Two are related to proxy servers, two to browser bars, one to printing images, and one to opening Office documents through a browser.
For more information, see Security Bulletin MS13-080 and Adobe Notes.
I wrote the article for TechNet Blog CZ/SK.