A security vulnerability has been reported in Ninja Forms 3.15.3.

The patched version 3.15.4 was released today and includes additional security hardening, including strengthened output escaping in the admin submission edit screen.

If your site is still running 3.15.3, check the plugin page directly. The update may not appear immediately in the WordPress dashboard.

Please update to 3.15.4 as soon as possible.

WordPress.org changelog:
Ninja Forms on WordPress.org