In the Ninja Forms Contact Form WordPress plugin before 3.4.34, the wp_ajax_nf_oauth_connect AJAX action was vulnerable to open redirect due to the use of a user supplied redirect parameter and no protection in place.
The wp_ajax_nf_oauth_disconnect from the Ninja Forms Contact Form – The Drag and Drop Form Builder for WordPress WordPress plugin before 3.4.34 had no nonce protection making it possible for attackers to craft a request to disconnect a site's OAuth connection.
An open redirect in the Ninja Forms plugin before 3.3.19.1 for WordPress allows Remote Attackers to redirect a user via the lib/StepProcessing/step-processing.php (aka submissions download page) redirect parameter.