The YouTube Video Inserter WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to a reflected $_SERVER["PHP_SELF"] value in the ~/adminUI/settings.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.2.1.0.
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-38327
https://plugins.trac.wordpress.org/browser/youtube-video-inserter/trunk/adminUI/settings.php#L67