The MP3 Audio Player WordPress plugin before 5.16 does not escape one of its audio player shortcode attributes before outputting it into an HTML attribute, allowing users with Contributor-level access and above to inject arbitrary JavaScript that executes when another user, such as an administrator previewing a pending post, views the content.

The MP3 Audio Player WordPress plugin before 5.16 does not escape one of its audio player shortcode attributes before outputting it into an HTML attribute, allowing users with Contributor-level access and above to inject arbitrary JavaScript that executes when another user, such as an administrator previewing a pending post, views the content.