==========================================================================
Ubuntu Security Notice USN-3456-1
October 17, 2017

xorg-server, xorg-server-hwe-16.04, xorg-server-lts-xenial vulnerabilities
==========================================================================

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

- Ubuntu 17.04
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in the X.Org X server.

Software Description:
- xorg-server: X.Org X11 server
- xorg-server-hwe-16.04: X.Org X11 server
- xorg-server-lts-xenial: X.Org X11 server

Details:

It was discovered that the X.Org X server incorrectly handled certain
lengths. An attacker able to connect to an X server, either locally or
remotely, could use these issues to crash the server, or possibly execute
arbitrary code.

Update instructions:

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

Ubuntu 17.04:
  xserver-xorg-core               2:1.19.3-1ubuntu1.3

Ubuntu 16.04 LTS:
  xserver-xorg-core               2:1.18.4-0ubuntu0.7
  xserver-xorg-core-hwe-16.04     2:1.19.3-1ubuntu1~16.04.4

Ubuntu 14.04 LTS:
  xserver-xorg-core               2:1.15.1-0ubuntu2.11
  xserver-xorg-core-lts-xenial    2:1.18.3-1ubuntu2.3~trusty4

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

References:
  https://www.ubuntu.com/usn/usn-3456-1
  CVE-2017-12176, CVE-2017-12177, CVE-2017-12178, CVE-2017-12179,
  CVE-2017-12180, CVE-2017-12181, CVE-2017-12182, CVE-2017-12183,
  CVE-2017-12184, CVE-2017-12185, CVE-2017-12186, CVE-2017-12187

Package Information:
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.19.3-1ubuntu1.3
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.18.4-0ubuntu0.7

https://launchpad.net/ubuntu/+source/xorg-server-hwe-16.04/2:1.19.3-1ubuntu1~16.04.4
  https://launchpad.net/ubuntu/+source/xorg-server/2:1.15.1-0ubuntu2.11

https://launchpad.net/ubuntu/+source/xorg-server-lts-xenial/2:1.18.3-1ubuntu2.3~trusty4