1. Ubuntu Security Notices
  2. USN-6168-2

USN-6168-2: libx11 vulnerability

Publication date

20 June 2023

Overview

libx11 could be made to crash if it received specially crafted network traffic.

Releases

Packages

  • libx11 - X11 client-side library

Details

USN-6168-1 fixed a vulnerability in libx11. This update provides
the corresponding update for Ubuntu 14.04 ESM, Ubuntu 16.04 ESM,
and Ubuntu 18.04 ESM.

Original advisory details:

Gregory James Duck discovered that libx11 incorrectly handled certain
Request, Event, or Error IDs. If a user were tricked into connecting to a
malicious X Server, a remote attacker could possibly use this issue to
cause libx11 to crash, resulting in a denial of service.

USN-6168-1 fixed a vulnerability in libx11. This update provides
the corresponding update for Ubuntu 14.04 ESM, Ubuntu 16.04 ESM,
and Ubuntu 18.04 ESM.

Original advisory details:

Gregory James Duck discovered that libx11 incorrectly handled certain
Request, Event, or Error IDs. If a user were tricked into connecting to a
malicious X Server, a remote attacker could possibly use this issue to
cause libx11 to crash, resulting in a denial of service.

Update instructions

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
18.04 bionic libx11-6 –  2:1.6.4-3ubuntu0.4+esm1  
16.04 xenial libx11-6 –  2:1.6.3-1ubuntu2.2+esm2  
14.04 trusty libx11-6 –  2:1.6.2-1ubuntu2.1+esm3  

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References

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