In case anyone needs it, here is the command line to patch fail2ban:
sudo apt-get update
sudo apt-get install --only-upgrade fail2ban
Although it's considered best practice to upgrade all packages, like this:
sudo apt-get update
sudo apt-get upgrade
sudo apt-get update
sudo apt-get install --only-upgrade fail2ban
Although it's considered best practice to upgrade all packages, like this:
sudo apt-get update
sudo apt-get upgrade
So if you have not installed sudo, or do not have permission to use it, then you should use "su - " to become root, then run "apt-get update;apt-get upgrade".