Read the full story https://wordpress.org/news/2017/08/wordpress-4-8-1-maintenance-release/
After over 13 million downloads of WordPress 4.8, we are pleased to announce the immediate availability of WordPress 4.8.1, a maintenance release.
This release contains 29 maintenance fixes and enhancements, chief among them are fixes to the rich Text widget and the introduction of the Custom HTML widget. For a full list of changes, consult the release notes, the tickets closed, and the list of changes.
Download WordPress 4.8.1 or visit Dashboard → Updates and simply click “Update Now.” Sites that support automatic background updates are already beginning to update to WordPress 4.8.1.
Thanks to everyone who contributed to 4.8.1:
Adam Silverstein, Andrea Fercia, Andrew Ozz, Atanas Angelov, bonger, Boone Gorges, Boro Sitnikovski, David Herrera, James Nylen, Jeffrey Paul, Jennifer M. Dodd, K. Adam White, Konstantin Obenland, Mel Choyce, r-a-y, Reuben Gunday, Rinku Y, Said El Bakkali, Sergey Biryukov, Siddharth Thevaril, Timmy Crawford, and Weston Ruter.