MediaWiki 1.3.8 and earlier, when used with Apache mod_mime, does not properly handle files with two file extensions, such as .php.rar, which allows remote attackers to upload and execute arbitrary code.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2004-1402
http://www.securityfocus.com/bid/11985
http://wikipedia.sourceforge.net/