The Social Post Embed plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Threads embed handler in all versions up to, and including, 2.0.1. This is due to insufficient input sanitization and output escaping on the user-supplied URL. 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/browser/social-post-embed/trunk/inc/threads.php#L64
https://plugins.trac.wordpress.org/browser/social-post-embed/tags/2.0.2/inc/threads.php#L61
https://plugins.trac.wordpress.org/browser/social-post-embed/tags/2.0.2/inc/threads.php#L50
https://plugins.trac.wordpress.org/browser/social-post-embed/tags/2.0.2/inc/threads.php#L49
https://plugins.trac.wordpress.org/browser/social-post-embed/tags/2.0.1/inc/threads.php#L64