In WordPress before 4.7.3, there is authenticated Cross-Site Scripting (XSS) via Media File Metadata. This is demonstrated by both (1) mishandling of the playlist shortcode in the wp_playlist_shortcode function in wp-includes/media.php and (2) mishandling of meta information in the renderTracks function in wp-includes/js/mediaelement/wp-playlist.js.
https://wpvulndb.com/vulnerabilities/8765
https://github.com/WordPress/WordPress/commit/28f838ca3ee205b6f39cd2bf23eb4e5f52796bd7
http://www.securitytracker.com/id/1037959