On the evening of November 15, 2017, the new WordPress 4.9 Billy Tipton was released, in honor of the jazz musician of the same name. The new WordPress 4.9 came to make tasks like designing your page easier, but also to keep you safe from Mistakes in the code. 
Last night, Automattic released the first fix of 4.9, (4.9.), which comes to close some security gaps discovered in the previous one version.
So, according to developers, the following were fixed:
- #42573: File caching affecting users' ability to use the Plugin and theme file editors.
- #42574: MediaElement upgrade causing JS errors when certain languages are in use.
- #42579: Incorrect logic in
extract_from_markers(). - #42454: Unable to translate Codex URL in theme editor.
- #42609: Theme editor can not edit files when running on a Windows server.
- #42628:
flatten_dirlist()doesn't play nice with folders with numeric names. - #42634:
DB_HOSTsocket paths with colons not parsed correctly. - #42641: On multisite upgrade
wp_blog_versionstable doesn't get updated - #42673: Themes page throws console error when there is only one installed theme.
Let's note, however, that 57 is the version that brings many important internal changes:
The Customizer application has more features that allow you to save, schedule, or save drafts of the changes you made to the theme of your page.
So you can design your site with ease, and schedule when the changes you've made will be live.
Download the new version, or upgrade directly from the admin panel
