The August 2012 Cumulative Security Update for Internet Explorer is now available via Windows Update. This security update resolves four privately reported vulnerabilities in Internet Explorer. The most severe vulnerabilities could allow remote code execution if a user views a specially crafted Web page using Internet Explorer. An attacker who successfully exploited any of these vulnerabilities could gain the same user rights as the current user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights This security update is rated Critical for IE6, IE7, IE8 and IE9 on Windows clients and Moderate on Windows servers.
If you have enabled automatic updating then you do not need to take any action. If you haven't, then launch Windows Update from the start menu.
For more information, see the full bulletin.