In Joomla! 3.2.0 through 3.6.5 (fixed in 3.7.0), inadequate escaping of file and folder names leads to XSS vulnerabilities in the template manager component.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2017-16957
https://developer.joomla.org/security-centre/687-20170405-core-xss-vulnerability