MediaWiki before 1.19.24, 1.2x before 1.23.9, and 1.24.x before 1.24.2, when using HHVM or Zend PHP, allows remote attackers to cause a denial of service ("quadratic blowup" and memory consumption) via an XML file containing an entity declaration with long replacement text and many references to this entity, a different vulnerability than CVE-2015-2942.
http://www.mandriva.com/security/advisories?name=MDVSA-2015:200
http://www.openwall.com/lists/oss-security/2015/04/01/1
http://www.openwall.com/lists/oss-security/2015/04/07/3
http://www.securityfocus.com/bid/73477
https://lists.wikimedia.org/pipermail/mediawiki-announce/2015-March/000175.html