Mediawiki before 1.28.1 / 1.27.2 contains an unsafe use of temporary directory, where having LocalisationCache directory default to system tmp directory is insecure.
Mediawiki before 1.28.1 / 1.27.2 / 1.23.16 contains a flaw were Spam blacklist is ineffective on encoded URLs inside file inclusion syntax's link parameter.
MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 has XSS when the $wgShowExceptionDetails setting is false and the browser sends non-standard URL escaping.