The Quiz extension for MediaWiki allows remote attackers to cause a denial of service via regex metacharacters in a regular expression.
www.openwall.com/lists/oss-security/2015/08/12/6
www.openwall.com/lists/oss-security/2015/08/27/6
www.securityfocus.com/bid/76362
lists.fedoraproject.org/pipermail/package-announce/2015-August/165193.html
lists.wikimedia.org/pipermail/mediawiki-announce/2015-August/000179.html
security.gentoo.org/glsa/201510-05