The Carta Online plugin for WordPress is vulnerable to Stored Cross-Site Scripting via admin settings in all versions up to, and including, 2.13.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.
https://plugins.trac.wordpress.org/browser/carta-online/trunk/carta-online.php#L417
https://plugins.trac.wordpress.org/browser/carta-online/tags/2.13.0/carta-online.php#L417