The NotificationX plugin for WordPress is vulnerable to Missing Authorization leading to...

The NotificationX plugin for WordPress is vulnerable to Missing Authorization leading to arbitrary content injection in versions up to, and including, 3.3.3 The /notificationx/v1/popup-submit REST route is registered with permission_callback => '__return_true', and the handler at PopupNotification::handle_popup_submission() accepts an attacker-controlled nx_id, loads whichever NotificationX campaign that id points to, and copies that campaign's own source into the new entry without verifying that the campaign is a Popup Notification or Exit Intent Popup (the two sources this form is intended to serve). This makes it possible for unauthenticated attackers to inject forged social-proof entries (name, title, message, email, theme) into any enabled non-popup NotificationX campaign — WP Comments, WooCommerce/EDD/Give sales, reviews, etc.