One of the benefits of having a managed WordPress host is the fact that Pressable takes care of any updates of WordPress core. Known security vulnerabilities in wordpress.org hosted plugins are also removed automatically by our systems. Security patches to WordPress core (X.X.X) are applied within an hour of release. With Major releases (X.X) are applied within 2 weeks of release on average.
You are responsible for keeping your Theme and any commercial Plugins updated.