source: http://www.securityfocus.com/bid/3767/info

A flaw exists in Microsoft Internet Explorer that may allow a remote attacker to view known files on a target system when a user views web content containing a specially crafted script.

The problem occurs when the 'GetObject()' JScript function is used with the ActiveX object 'htmlfile.' If a URL containing "../" sequences is passed as the first argument to the function, it is possible to cause Internet Explorer to grant full access to the DOM of the created HTML document object:

a=GetObject("http://"+location.host+"/../../../../../../test.txt","htmlfile");

This vulnerability could be used by a malicious web site administrator to view any known file on a target system. It may also lead to the execution of arbitrary code.