USN-4656-1: X.Org X Server vulnerabilities

01 December 2020

Several security issues were fixed in X.Org X Server.



  • xorg-server - X.Org X11 server
  • xorg-server-hwe-16.04 - X.Org X11 server
  • xorg-server-hwe-18.04 - X.Org X11 server


Jan-Niklas Sohn discovered that the X.Org X Server XKB extension
incorrectly handled certain inputs. A local attacker could possibly use
this issue to escalate privileges.

Update instructions

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

Ubuntu 20.10
Ubuntu 20.04
Ubuntu 18.04
Ubuntu 16.04

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

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