Facebook Cross-Site Request Forgery

The wp_ajax_save_fbe_settings and wp_ajax_delete_fbe_settings AJAX actions of the Facebook for WordPress plugin before 3.0.4 were vulnerable to CSRF due to a lack of nonce protection. The settings in the saveFbeSettings function had no sanitization allowing for script tags to be saved. (2021-04-12, CVE-2021-24218)

The absence of Anti-CSRF tokens may lead to a Cross-Site Request Forgery attack that can result in executing a specific application action as another logged in user, e.g. steal their account by changing their email and password or silently adding a new admin user account when executed from the administrator account.

The attacker may copy one of your web application forms, e.g. email/password change form.

The webpage will contain a form with the exact set of fields as the original application but with input values already provided and the submit button replaced with a Javascript code causing auto-submission. When the page is accessed the form will be immediately submitted and page contents replaced with a valid content or a redirect to your original application.

One of your application users who is already logged in can be then tricked to navigate to such malicious page e.g. by clicking a link in a phishing email, and the pre-populated form content will be submitted to your application like it would be submitted by your user.