A libXfixes security update has been released for Ubuntu Linux 16.04 ESM.

USN-5437-1: libXfixes vulnerability

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Ubuntu Security Notice USN-5437-1
May 23, 2022

libxfixes vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 ESM

Summary:

libXfixes could be made to crash or run programs if it received specially
crafted input.

Software Description:
- libxfixes: X11 miscellaneous fixes extension library

Details:

Tobias Stoeckmann discovered that libXfixes incorrectly handled certain
inputs. An attacker could possibly use this issue to cause a denial
of service, or possibly execute arbitrary code.

Update instructions:

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

Ubuntu 16.04 ESM:
libxfixes3 1:5.0.1-2ubuntu0.1~esm1

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-5437-1
CVE-2016-7944