Updated X.org X server packages has been released for Ubuntu Linux 18.10, 18.04 LTS, and 16.04 LTS

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Ubuntu Security Notice USN-3802-1
October 26, 2018

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

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
https://usn.ubuntu.com/usn/usn-3802-1
CVE-2018-14665

Package Information:
https://launchpad.net/ubuntu/+source/xorg-server/2:1.20.1-3ubuntu2.1
https://launchpad.net/ubuntu/+source/xorg-server/2:1.19.6-1ubuntu4.2

https://launchpad.net/ubuntu/+source/xorg-server-hwe-16.04/2:1.19.6-1ubuntu4.1~16.04.2

  X.Org X Security Update for Ubuntu Linux