Manual:$wgMimeTypeBlacklist

Details
Files with these mime types will never be allowed as uploads if $wgVerifyMimeType is enabled.

Default value

 * 'application/x-opc+zip', 'application/msword', 'application/vnd.ms-powerpoint', 'application/vnd.msexcel' where introduced after 1.17.0 (see SVN change)
 * 'application/x-opc+zip', 'text/scriptlet', 'application/x-msdownload' were introduced after 1.5.5
 * 'application/x-msmetafile' was added in 1.5.5, 'application/zip' in
 * All other values were available since the setting was introduced in 1.5.0