This is a minor (point) release in the 4MLinux STABLE channel, which comes with the Linux kernel 4.9.40. The 4MLinux Server now includes Apache 2.4.27, MariaDB 10.2.7, and PHP 7.0.21 (see this post for more details). Additionally, some popular programs (Chromium, Java, PeaZip, SMTube) have been updated, too.
The 4MLinux ISO is about 100 MB bigger (than it used to be) due to the changes in the 4MLinux initrd image, which now includes the full set of the Linux firmware to provide better support for modern Ethernet and WiFi cards.
You can update your 4MLinux by executing the "zk update" command in your terminal (fully automatic process).