Technical Information

Brief overview of the risk:
This security update resolves a privately reported vulnerability in the JScript and VBScript scripting engines on 64-bit versions of Microsoft Windows. The vulnerability could allow remote code execution if a user visited a specially crafted website.
Detailed Information on the risk:

A remote code execution vulnerability exists in the way that the JScript and VBScript engines calculate the size of an object in memory during a copy operation. The vulnerability may corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system.

Further information on this exploit is available at : MS12-056