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.
This is a vulnerability exploitable with network access which means the vulnerable software is bound to
the network stack and the attacker does not require local network access or local access to exploit it.
Such a vulnerability is often termed “remotely exploitable”.
The access conditions are somewhat specialized; the following are examples:
The attacking party is limited to a group of systems or users at some level of authorization, possibly untrusted.
Some information must be gathered before a successful attack can be launched.
The affected configuration is non-default, and is not commonly configured (e.g., a vulnerability present when a
server performs user account authentication via a specific scheme, but not present for another authentication scheme).
The attack requires a small amount of social engineering that might occasionally fool cautious users (e.g.,
phishing attacks that modify a web browser’s status bar to show a false link, having to be on someone’s “buddy”
list before sending an IM exploit).
Authentication is not required to access and exploit the vulnerability.
There is total information disclosure, resulting in all system files being revealed. The
attacker is able to read all of the system's data (memory, files, etc.).
There is no impact to the integrity of the system.
There is no impact to the availability of the system.