The HLS Player plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'hls_player' shortcode in all versions up to, and including, 1.0.10 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
https://plugins.trac.wordpress.org/changeset/3197684/hls-player/tags/1.0.11/hls-player.php