USN-3802-1: X.Org X server vulnerability

26 October 2018

xorg-server, xorg-server-hwe-16.04 vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 18.10
  • Ubuntu 18.04 LTS
  • Ubuntu 16.04 LTS

Summary

X.Org X server could be made to overwrite files as the administrator.

Software Description

  • xorg-server - X.Org X11 server
  • xorg-server-hwe-16.04 - X.Org X11 server

Details

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.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 18.10
xserver-xorg-core - 2:1.20.1-3ubuntu2.1
Ubuntu 18.04 LTS
xserver-xorg-core - 2:1.19.6-1ubuntu4.2
Ubuntu 16.04 LTS
xserver-xorg-core-hwe-16.04 - 2:1.19.6-1ubuntu4.1~16.04.2

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.

References