MediaWiki is a collaborative editing software, used by big projects like Wikipedia.
A security audit of the MediaWiki project discovered that MediaWiki is vulnerable to several cross-site scripting and cross-site request forgery attacks, and that the image deletion code does not sufficiently sanitize input parameters.
By tricking a user to load a carefully crafted URL, a remote attacker could hijack sessions and authentication cookies to inject malicious script code that will be executed in a user's browser session in context of the vulnerable site, or use JavaScript submitted forms to perform restricted actions. Using the image deletion flaw, it is also possible for authenticated administrators to delete arbitrary files via directory traversal.
There is no known workaround at this time.
All MediaWiki users should upgrade to the latest available version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-apps/mediawiki-1.3.11"