Multiple vulnerabilities have been reported in MediaWiki, which can be exploited by malicious users to conduct script insertion attacks and by malicious people to disclose potentially sensitive information and conduct cross-site request forgery attacks.

1) The application allows users to perform certain actions via HTTP requests without performing any validity checks to verify the requests. This can be exploited to e.g. block or unblock a user by tricking a logged in administrator into visiting a malicious web site.

2) An error due to the application failing to restrict access to the user.tokens module can be exploited to disclose a user's CSRF tokens.

3) Certain unspecified input passed to the wikitext parser when creating a page is not properly sanitised before being used. This can be exploited to insert arbitrary HTML and script code, which will be executed in a user's browser session in context of an affected site when the malicious data is being viewed.

Note: This can further be exploited to cause an infinite loop and exhaust memory.

The vulnerabilities are reported in versions prior to 1.17.3 and 1.18.2.

Solution
Update to version 1.17.3 or 1.18.2.

Provided and/or discovered by
1) The vendor credits Krenair
2) Reported in a MediaWiki bug ticket by Brion Vibber
3) Reported in a MediaWiki bug ticket by Bawolff Bawolff

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://lists.wikimedia.org/pipermail/mediawiki-announce/2012-March/000109.html
http://lists.wikimedia.org/pipermail/mediawiki-announce/2012-March/000110.html

Deep Links
Links available to Secunia VIM customers