--- title: 'USN-6168-2: libx11 vulnerability | Ubuntu security notices' description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/notices/USN-6168-2 --- 1. [Ubuntu Security Notices](https://ubuntu.com/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 [18.04 LTS](https://ubuntu.com/security/notices?release=bionic) [16.04 LTS](https://ubuntu.com/security/notices?release=xenial) [14.04 LTS](https://ubuntu.com/security/notices?release=trusty) --- Open side navigation ## Packages * [libx11](https://ubuntu.com/security/cves?package=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. ## 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.](https://ubuntu.com/security/cves/about#security) The problem can be corrected by updating your system to the following package versions: | Ubuntu Release | Package Version | | --- | --- | | 18.04 LTS bionic | [libx11-6](https://launchpad.net/ubuntu/+source/libx11) –  2:1.6.4-3ubuntu0.4+esm1   Ubuntu Pro | | | | 16.04 LTS xenial | [libx11-6](https://launchpad.net/ubuntu/+source/libx11) –  2:1.6.3-1ubuntu2.2+esm2   Ubuntu Pro | | | | 14.04 LTS trusty | [libx11-6](https://launchpad.net/ubuntu/+source/libx11) –  2:1.6.2-1ubuntu2.1+esm3   Ubuntu Pro | | | --- ### Reduce your security exposure Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines. [Get Ubuntu Pro](https://ubuntu.com/pro) ## References * [CVE-2023-3138](https://ubuntu.com/security/CVE-2023-3138) ## Related notices * [USN-6168-1](https://ubuntu.com/security/notices/USN-6168-1)