Thiago Zaninotti has discovered a vulnerability in Apache HTTP Server, which can be exploited by malicious people to conduct cross-site scripting attacks.

Input passed to the "Expect:" header is not properly sanitised before being returned to users. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of a vulnerable site.

The vulnerability affects versions prior to 1.3.35, 2.0.58, and 2.2.2.

NOTE: This issue was originally not considered a vulnerability by the researcher and vendor due to the fact that no known vectors existed to exploit it. However, additional research by Amit Klein has proven that this can be exploited via a specially crafted Flash file.

Solution
Update to version 1.3.35, 2.0.58, 2.2.2, or later.

Provided and/or discovered by
Thiago Zaninotti

Additional information about exploitation:
Amit Klein

Changelog
Further details available to Secunia VIM customers

Original Advisory
Vendor bug report:
http://svn.apache.org/viewvc?view=rev&revision=394965

Thiago Zaninotti:
http://archives.neohapsis.com/archives/bugtraq/2006-05/0151.html

Amit Klein:
http://archives.neohapsis.com/archives/bugtraq/2006-07/0425.html

Deep Links
Links available to Secunia VIM customers