The TalkJS plugin for WordPress is vulnerable to Stored Cross-Site Scripting via admin settings in all versions up to, and including, 0.1.15 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/talkjs/trunk/classes/admin/ui/SettingsPage.php#L276
https://plugins.trac.wordpress.org/browser/talkjs/trunk/classes/admin/ui/FieldBuilder.php#L147
https://plugins.trac.wordpress.org/browser/talkjs/tags/0.1.15/classes/admin/ui/SettingsPage.php#L276
https://plugins.trac.wordpress.org/browser/talkjs/tags/0.1.15/classes/admin/ui/FieldBuilder.php#L147