The setRequestHeader method of the XMLHttpRequest object in Microsoft Internet Explorer 5.01, 6, and 7 does not block dangerous HTTP request headers when certain 8-bit character sequences are appended to a header name, which allows remote attackers to (1) conduct HTTP request splitting and HTTP request smuggling attacks via an incorrect Content-Length header, (2) access arbitrary virtual hosts via a modified Host header, (3) bypass referrer restrictions via an incorrect Referer header, and (4) bypass the same-origin policy and obtain sensitive information via a crafted request header.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5291
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2008/ms08-031
http://www.vupen.com/english/advisories/2008/1778
http://www.vupen.com/english/advisories/2008/0980
http://www.us-cert.gov/cas/techalerts/TA08-162B.html
http://www.securitytracker.com/id?1020226
http://www.securityfocus.com/bid/28379
http://www.securityfocus.com/archive/1/489954/100/0/threaded
http://www.mindedsecurity.com/MSA02240108.html
http://securityreason.com/securityalert/3785