Update the WordPress Defender Security plugin to the latest available version (at least 3.3.3).
Calvin Alkan discovered and reported this Broken Authentication vulnerability in WordPress Defender Security Plugin. This can be abused by a malicious actor to perform action which normally should only be able to be executed by higher privileged users. These actions might allow the malicious actor to gain admin access to the website. This vulnerability has been fixed in version 3.3.3.