Well, safety is not guaranteed anywhere. It is possible that you have used poor coding plugins and more than one plugin for the same thing. Any plugin that is not compatible with your website theme can be many more. Hackers play tricks here, and they try to get access to your website via any poor plugin. It is one of the main reasons people recommend using trustable or reputable 3rd party plugins. Many plugins provide security to your website. And you can use one of them.