source: http://www.securityfocus.com/bid/3513/info

Internet Explorer contains a vulnerability, which could allow an attacker to construct a URL that would display or modify the cookie information associated with an arbitrary website.

If a URL is composed in the about: protocol referencing a website, Javascript embedded in the URL can access any cookies associated with that website via 'document.cookie'. The Javascript executes because of a cross-site scripting condition in the about: protocol. 

about://www.google.com/<script language=javascript>alert(document.cookie);</script>