WordPress 4.9.3 contains 34 bug fixes.
Things to note
WordPress 4.9.3 should be appplied to your site(s) in order to address the bugs fixed in the Customizer, widgets, visual editor, and PHP 7.2 compatibility. You can read more by looking at the release notes: https://codex.wordpress.org/Version_4.9.3
If you have not done so already – download the update or simply use your existing installation of WordPress to update your site. Either way – this is an excellent time to make a backup copy of your site(s) before upgrading.