X.Org X server could be made to overwrite files as the administrator.
Narendra Shinde discovered that the X.Org X server incorrectly handled certain command line parameters when running as root with the legacy wrapper. When certain graphics drivers are being used, a local attacker could possibly use this issue to overwrite arbitrary files and escalate privileges.
26 October 2018
A security issue affects these releases of Ubuntu and its derivatives:
X.Org X server could be made to overwrite files as the administrator.
Narendra Shinde discovered that the X.Org X server incorrectly handled certain command line parameters when running as root with the legacy wrapper. When certain graphics drivers are being used, a local attacker could possibly use this issue to overwrite arbitrary files and escalate privileges.
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.