A libx11 security update has been released for Ubuntu Linux 20.04 LTS, 18.04 LTS, and 16.04 LTS.

USN-4487-1: libx11 vulnerabilities

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Ubuntu Security Notice USN-4487-1
September 02, 2020

libx11 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in libx11.

Software Description:
- libx11: None

Details:

Todd Carson discovered that libx11 incorrectly handled certain memory
operations. A local attacker could possibly use this issue to escalate
privileges. (CVE-2020-14344)

Jayden Rivers discovered that libx11 incorrectly handled locales. A local
attacker could possibly use this issue to escalate privileges.
(CVE-2020-14363)

Update instructions:

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

Ubuntu 20.04 LTS:
libx11-6 2:1.6.9-2ubuntu1.1

Ubuntu 18.04 LTS:
libx11-6 2:1.6.4-3ubuntu0.3

Ubuntu 16.04 LTS:
libx11-6 2:1.6.3-1ubuntu2.2

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

References:
  https://usn.ubuntu.com/4487-1
CVE-2020-14344, CVE-2020-14363

Package Information:
  https://launchpad.net/ubuntu/+source/libx11/2:1.6.9-2ubuntu1.1
  https://launchpad.net/ubuntu/+source/libx11/2:1.6.4-3ubuntu0.3
  https://launchpad.net/ubuntu/+source/libx11/2:1.6.3-1ubuntu2.2