A libx11 security update has been released for Ubuntu Linux 14.04 ESM and 12.04 ESM.

USN-4487-2: libx11 vulnerabilities

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Ubuntu Security Notice USN-4487-2
September 08, 2020

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

- Ubuntu 14.04 ESM
- Ubuntu 12.04 ESM

Summary:

Several security issues were fixed in libx11.

Software Description:
- libx11: None

Details:

USN-4487-1 fixed several vulnerabilities in libx11. This update provides
the corresponding update for Ubuntu 12.04 ESM and 14.04 ESM.

Original advisory 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 14.04 ESM:
libx11-6 2:1.6.2-1ubuntu2.1+esm1

Ubuntu 12.04 ESM:
libx11-6 2:1.4.99.1-0ubuntu2.5

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

References:
  https://usn.ubuntu.com/4487-2
  https://usn.ubuntu.com/4487-1
CVE-2020-14344, CVE-2020-14363