Description: This security update resolves a privately reported vulnerability in the JScript scripting engine that could allow remote code execution if a user opened a specially crafted file or visited a specially crafted Web site and invoked a malformed script. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. 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 addresses the vulnerability by modifying the way that the JScript engine processes scripts in Web pages.

Update type: Critical

Release date: November 10, 2009

Applies to: All versions

Knowledge base: support.microsoft.com/kb/971961

Download link: 32-bit | 64-bit
Comments:There are multiple downloads, depending on the version of Internet Explorer you have. The links in this post are for IE7, which comes with Vista. Check here for the version that is specific to your setup.

Here are the specifics on the vulnerabilities covered by this update:

• JScript Remote Code Execution Vulnerability – CVE-2009-1920