WordPress version 3.9.2 is an important security release and is now available for download. If you have not updated (or are not set up for automatic background updates) – take some time to backup your site and update.

You can read more about the update: https://core.trac.wordpress.org/log/branches/3.9?stop_rev=29383&rev=29411

You can download WordPress 3.9.2: http://wordpress.org/wordpress-3.9.2.zip