Just like to point out..
That while this bug sucks, it may not effect all users of systemd with those versions.
I have many systems running systemd and not one of them have systemd-resolver active. Thus, those systems are immune even though they are running an effected systemd version.
When running systemd there is no requirement to use systemd-resolver and typically you (or your distro) will need to manually enable it.
So before you panic run:
systemctl status systemd-resolved
If disabled you'll get one of two messages depending on distro:
$ systemctl status systemd-resolved
Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; disabled; v
Active: inactive (dead)
or
$ systemctl status systemd-resolved
Unit systemd-resolved.service could not be found.
If you get either of these responses, you're safe.