Oracle finally made the Virtualbox binary packages for Ubuntu 14.10 Utopic available in its official Linux repository. Which means running regular system updates via Software Updater will keep your Virtualbox release always up-to-date.
While Ubuntu 14.10 repositories provide the Virtualbox 4.3.18, the latest has reached the version 4.3.20. For the changelog, see the web page.
How to Add Virtualbox Repository in Ubuntu:
Open terminal from the Unity Dash or just press Ctrl+Alt+T on keyboard. When it opens, paste the command below into terminal and run to get the key:
wget -q -O - http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc | sudo apt-key add -
Type in your user password when it asks. Then run command to add the vbox repository for Ubuntu 14.10:
sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian utopic non-free contrib" >> /etc/apt/sources.list.d/virtualbox.org.list'
Now install Vbox 4.3 via your package manager after checking for updates. Or just run commands below one by one:
sudo apt-get update sudo apt-get install virtualbox-4.3
Finally keep your system up-to-date by running regular system updates, which also keep your Virutalbox 4.3 series up-to-date.