systemd-resolved would allow unprivileged users to change DNS settings.
It was discovered that the systemd-resolved D-Bus interface did not enforce appropriate access controls. A local unprivileged user could exploit this to modify a system’s DNS resolver settings.
3 September 2019
A security issue affects these releases of Ubuntu and its derivatives:
systemd-resolved would allow unprivileged users to change DNS settings.
It was discovered that the systemd-resolved D-Bus interface did not enforce appropriate access controls. A local unprivileged user could exploit this to modify a system’s DNS resolver settings.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to reboot your computer to make all the necessary changes.
Vulmon