Automattic developers released it yesterday evening new edition WordPress 4.9.5:
The updated version of the popular CMS (from content management system) is a maintenance version and comes to fix 28 errors of 4.9.4.
That's it change log says:
From the WordPress 4.9.5 release post: This maintenance release fixes 28 bugs in 4.9, including fixes for Customizer, media library, error notices, and some security fixes. Twenty Seventeen bundled theme and Hello Dolly bundled plugin have also been updated.
Of course as with any update, you should upgrade immediately, either with the λήψη of application from the official website, or from your admin panel in automatic mode.
Before proceeding with the upgrade it would be good to get a full one backup.