Security vulnerabilities are patched regularly in Ubuntu’s package repositories. unattended-upgrades automatically downloads and installs security updates — and optionally all updates — so your server stays protected without manual intervention. This guide configures it on Ubuntu 26.04 LTS.

Tested and valid on:

  • Ubuntu 26.04 LTS

Prerequisites

  • Ubuntu 26.04 LTS server
  • A user with sudo privileges
  • An email address for notifications (optional)

Step 1 – Install unattended-upgrades

The package is usually pre-installed. Install or confirm:

sudo apt install unattended-upgrades apt-listchanges -y

Step 2 – Enable Automatic Updates

Run the interactive configuration wizard:

sudo dpkg-reconfigure --priority=low unattended-upgrades

Select Yes to enable automatic updates.

Step 3 – Review the Main Configuration

Open the unattended-upgrades config file:

sudo nano /etc/apt/apt.conf.d/50unattended-upgrades

Confirm the Unattended-Upgrade::Allowed-Origins block includes security updates:

"${distro_id}:${distro_codename}-security";

Step 4 – Enable All Updates (optional)

To also apply regular package updates (not just security), uncomment:

"${distro_id}:${distro_codename}";

Step 5 – Configure Email Notifications

Set up email reports (requires a working mail setup):

Unattended-Upgrade::Mail "[email protected]";
Unattended-Upgrade::MailReport "on-change";

Step 6 – Enable Automatic Reboot (optional)

Allow automatic reboots after kernel updates (schedule at a quiet time):

Unattended-Upgrade::Automatic-Reboot "true";
Unattended-Upgrade::Automatic-Reboot-Time "03:00";

Step 7 – Test the Configuration

Perform a dry-run to confirm the setup is correct:

sudo unattended-upgrades --dry-run --debug 2>&1 | head -40

Step 8 – Check Logs

View the upgrade history:

cat /var/log/unattended-upgrades/unattended-upgrades.log

Conclusion

Unattended upgrades are now configured on your Ubuntu 26.04 LTS server. Security patches will be applied automatically, significantly reducing your exposure window to known vulnerabilities.