MediaWiki upstream has released new v1.15.2 version:
  http://lists.wikimedia.org/pipermail/mediawiki-announce/2010-March/000088.html

 of MediaWiki fixing two security issues (from upstream announcement):

a, "A CSS validation issue was discovered which allows editors to display
external images in wiki pages. This is a privacy concern on public
wikis, since a malicious user may link to an image on a server they
control, which would allow that attacker to gather IP addresses and
other information from users of the public wiki. All sites running
publicly-editable MediaWiki installations are advised to upgrade. All
versions of MediaWiki (prior to this one) are affected."

CVE identifier of CVE-2010-1189 has been assigned to this.

--

b, "A data leakage vulnerability was discovered in thumb.php which affects
wikis which restrict access to private files using img_auth.php, or
some similar scheme. All versions of MediaWiki since 1.5 are affected.

Deleting thumb.php is a suitable workaround for private wikis which do
not use $wgThumbnailScriptPath or $wgLocalRepo['thumbScriptUrl']."

CVE identifier of CVE-2010-1190 has been assigned to this.

Upstream patch:
  http://download.wikimedia.org/mediawiki/1.15/mediawiki-1.15.2.patch.gz

References:
  http://secunia.com/advisories/38856/

CVE Request:
  http://www.openwall.com/lists/oss-security/2010/03/09/4