This post is in no way aimed at bashing systemd. It simply demonstrates a simple but crazy bug in systemd that could cause so much trouble for the sysadmins.

NOTIFY_SOCKET=/run/systemd/notify systemd-notify ""

Run the above command on a systemd machine, by any user and you will cause a DOS on that machine. Without getting much into the technical aspects of the bug, I’ll demonstrate what actually happens if someone run the above command.

Check this out:

I’m running the command on a Linux Mint 18 machine, which uses systemd. Systemd 1

And there. You can no longer restart any services, or not even reboot the system. This is what happens when you try to reboot or restart any services.

Systemd 1

The serious thing about this bug is that any user on a system can do this and that will cause a lot of problems ( if that wasn’t so obvious :D ).

For more technical information about the bug, go here

The guy who discovered this vulnerability ( yes, I’d call this a security vulnerability ) has already opened the issue in systemd gitub page.
You can see the status of the bug here :