The WPC Order Notes for WooCommerce plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.5.2. This is due to missing or incorrect nonce validation on the ajax_update_order_note() function. This makes it possible for unauthenticated attackers to inject malicious web scripts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
https://wordpress.org/plugins/woo-order-notes/#developers
https://plugins.trac.wordpress.org/changeset/3205072/
https://plugins.trac.wordpress.org/browser/woo-order-notes/trunk/wpc-order-notes.php#L416