A nginx security update has been released for Ubuntu Linux 14.04 ESM and 16.04 ESM.

USN-4967-2: nginx vulnerability

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Ubuntu Security Notice USN-4967-2
May 27, 2021

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

nginx could be made to crash or run programs if it received specially
crafted network traffic.

Software Description:
- nginx: small, powerful, scalable web/proxy server

Details:

USN-4967-1 fixed a vulnerability in nginx. This update provides
the corresponding update for Ubuntu 14.04 ESM and 16.04 ESM.

Original advisory details:

Luis Merino, Markus Vervier, and Eric Sesterhenn discovered that nginx
incorrectly handled responses to the DNS resolver. A remote attacker could
use this issue to cause nginx to crash, resulting in 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:
nginx 1.10.3-0ubuntu0.16.04.5+esm1
nginx-common 1.10.3-0ubuntu0.16.04.5+esm1
nginx-core 1.10.3-0ubuntu0.16.04.5+esm1
nginx-extras 1.10.3-0ubuntu0.16.04.5+esm1
nginx-full 1.10.3-0ubuntu0.16.04.5+esm1
nginx-light 1.10.3-0ubuntu0.16.04.5+esm1

Ubuntu 14.04 ESM:
nginx 1.4.6-1ubuntu3.9+esm2
nginx-common 1.4.6-1ubuntu3.9+esm2
nginx-core 1.4.6-1ubuntu3.9+esm2
nginx-extras 1.4.6-1ubuntu3.9+esm2
nginx-full 1.4.6-1ubuntu3.9+esm2
nginx-light 1.4.6-1ubuntu3.9+esm2

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

References:
  https://ubuntu.com/security/notices/USN-4967-2
  https://ubuntu.com/security/notices/USN-4967-1
CVE-2021-23017