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.
MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2, when a private wiki is configured, provides different error messages for failed login attempts depending on whether the username exists, which allows remote attackers to enumerate account names and conduct brute-force attacks via a series of requests.
The implementation of raw message parameter expansion in MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows HTML mangling attacks.
MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows remote attackers to inject > (greater than) characters via the id attribute of a headline.