WordPress 5.1.1 is now available. This is a security and maintenance release for WordPress 5.1 and earlier. It introduces 14 fixes and enhancements, including changes designed to help hosts prepare users for the minimum PHP version bump coming in 5.2.
While WordPress.org already started automatic background updates that do not require you to do anything, it may take some time for them to get to your website. If it does not update automatically today, either do it yourself (and don’t forget to make a full backup first!) or contact Dusk Owl for help.