In Joomla! 3.2.0 through 3.6.5 (fixed in 3.7.0), inadequate MIME type checks allowed low-privilege users to upload swf files even if they were explicitly forbidden.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2017-16959
https://developer.joomla.org/security-centre/689-20170407-core-acl-violations