Microsoft XML Core Services (MSXML) includes the XMLHTTP ActiveX control, which allows web pages rendering in the browser to send or receive XML data via HTTP operations such as POST, GET, and PUT. The control provides security measures designed to restrict web pages so they can only use the control to request data from remote data sources.

A flaw exists in how the XMLHTTP control applies IE security zone settings to a redirected data stream returned in response to a request for data from a web site. A vulnerability results because an attacker could seek to exploit this flaw and specify a data source that is on the user?s local system. The attacker could then use this to return information from the local system to the attacker?s web site. An attacker would have to entice the user to a site under his control to exploit this vulnerability. It cannot be exploited by HTML email. In addition, the attacker would have to know the full path and file name of any file he would attempt to read. Finally, this vulnerability does not give an attacker any ability to add, change or delete data.