Visual truncation vulnerability in Microsoft Internet Explorer 7 allows remote attackers to spoof the address bar and possibly conduct phishing attacks via a malicious URL containing non-breaking spaces (%A0), which causes the address bar to omit some characters from the URL.
https://exchange.xforce.ibmcloud.com/vulnerabilities/29827
http://www.securityfocus.com/archive/1/449917/100/0/threaded
http://www.kb.cert.org/vuls/id/347188
http://securitytracker.com/id?1017122
http://blogs.technet.com/msrc/archive/2006/10/26/ie-address-bar-issue.aspx