Contao CMS 2.9.2 - Persistent Cross Site Scripting Issue

Details
=============
Product: Contao CMS 2.9.2
Security-Risk: moderated
Remote-Exploit: yes
Vendor-URL: http://www.contao.org/
Advisory-Status: published

Credits
=============
Discovered by: David Vieira-Kurz

Affected Products:
=============
Contao CMS 2.9.2
Prior versions may also be vulnerable

Description
=============
"Contao is an open source content management system (CMS) for people who
want a professional internet presence that is easy to maintain." - from
www.contao.org

More Details
=============

I have discovered some vulnerabilities in Contao CMS 2.9.2, which can be
exploited by malicious people to conduct persistent cross-site scripting
attacks. Input passed directly over the "HTTP_X_FORWARDED_FOR" header in
"/system/libraries/Environment.php" is not properly sanitised before
being stored and returned to the user out from the
"/system/modules/comments/Comments.php" file when the user browses the
"/contao/main.php?do=comments" site. This can be exploited to execute
arbitrary HTML and script code in a user's browser session in context of
an affected site.

Solution
=============
Update to the patched version 2.9.3.

Timeline
================
2010-12-24, vendor informed ( see ticket 2751 )
2011-01-01, vendor confirmed the issue
2011-01-06, vendor relased a patched version(2.9.3)
2011-01-12, advisory published

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================

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