Ubuntu Security Notice USN-4905-2
June 30, 2021

xorg-server vulnerability

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

- Ubuntu 14.04 ESM


X.Org X Server could be made to crash or run programs if it received
specially crafted input.

Software Description:
- xorg-server: X.Org X11 server


USN-4905-1 fixed a vulnerability in X.Org. This update provides
the corresponding update for Ubuntu 14.04 ESM.

Original advisory details:

 Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled
 certain lengths of XInput extension ChangeFeedbackControl requests. An
 attacker could use this issue to cause the server to crash, resulting in a
 denial of service, or possibly execute arbitrary code.

Update instructions:

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

Ubuntu 14.04 ESM:
  xserver-xorg-core               2:1.15.1-0ubuntu2.11+esm4

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