The Third maintenance release of the long term support release Ubuntu 16.04.3 LTS is available to download and upgrade for those currently using it.
Ubuntu 16.04.3 comes with LTS Enablement Stacks which brings new Linux Kernels currently available for regular release to the long term support releases including the Ubuntu Xenial. It brings support for a newer hardware in the market which makes sense since the long term support release are supported for 5 years, however, the regular releases are supported for 9 months only. Currently, the latest Linux Kernel available for Ubuntu 16.04.3 is Linux Kernel 4.10.0-27.
It brings many bug fixes and improvements for the Desktop and Server releases. Check the release announcements for Ubuntu 16.04.3 LTS Here.
How To Upgrade to Ubuntu 16.04.3 LTS (Xenial Xerus)
If you are currently running Ubuntu 16.04 you will receive the latest updates. Use the keyboard shortcuts Alt+F2 and open the Update Manager. Type “update-manager” without quotes. For other releases of Ubuntu make sure you have selected “long-term support versions” from the “Update” tab on (Software & Updates) applications.
Install “update-manager-core” package if you don’t have it. Run the terminal and use the following commands.
sudo apt install update-manager-core
Check the release notes of Ubuntu 16.04.3 (Xenial Xerus) Here.