Ubuntu 20.04 LTS USN-4905-1 Critical: X.Org X Server DoS

ubuntu

April 13, 2021

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

Summary

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

- xorg-server-hwe-18.04: X.Org X11 server

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

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.

Topics Covered

security advisory denial of service DoS issue critical software update Ubuntu ubuntu program execution xorg-server X.Org xserver-xorg-core

Update Instructions

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

Ubuntu 20.10:
  xserver-xorg-core               2:1.20.9-2ubuntu1.3

Ubuntu 20.04 LTS:
  xserver-xorg-core               2:1.20.9-2ubuntu1.2~20.04.2

Ubuntu 18.04 LTS:
  xserver-xorg-core               2:1.19.6-1ubuntu4.9
  xserver-xorg-core-hwe-18.04     2:1.20.8-2ubuntu2.2~18.04.5

Ubuntu 16.04 LTS:
  xserver-xorg-core               2:1.18.4-0ubuntu0.12
  xserver-xorg-core-hwe-16.04     2:1.19.6-1ubuntu4.1~16.04.6

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