The Lottie Player plugin for WordPress is vulnerable to Stored Cross-Site Scripting via File uploads in all versions up to, and including, 1.1.8 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses the uploaded file.
https://wordpress.org/plugins/embed-lottie-player/#developers
https://plugins.trac.wordpress.org/browser/embed-lottie-player/tags/1.1.8/plugin.php#L82
https://plugins.trac.wordpress.org/browser/embed-lottie-player/tags/1.1.8/plugin.php#L130