From oss-security:


> I would like to announce the release of MediaWiki 1.16.5. Two security
> > issues were discovered.
> > 
> > The first issue is yet another recurrence of the Internet Explorer 6
> > XSS vulnerability that caused the release of 1.16.4. It was pointed
> > out that there are dangerous extensions with more than four
> > characters, so the regular expressions we introduced had to be updated
> > to match longer extensions.
> > 
> > For more details, see
> > https://bugzilla.wikimedia.org/show_bug.cgi?id=28534
Use CVE-2011-1765

> > 
> > The second issue allows unauthenticated users to gain additional
> > rights, on wikis where $wgBlockDisablesLogin is enabled. By default,
> > it is disabled. The issue occurs when a malicious user sends cookies
> > which contain the user name and user ID of a "victim" account. In
> > certain circumstances, the rights of the victim are loaded and persist
> > throughout the malicious request, allowing the malicious user to
> > perform actions with the victim's rights.
> > 
> > $wgBlockDisablesLogin is a feature which is sometimes used on private
> > wikis to prevent users who have an account from logging in and viewing
> > content on the wiki.
> > 
> > For more details, see
> > https://bugzilla.wikimedia.org/show_bug.cgi?id=28639
> > 
Use CVE-2011-1766