A nginx security update has been released for Ubuntu Linux 18.04, 20.04 LTS, 20.10, and 21.04.

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Ubuntu Security Notice USN-4967-1
May 26, 2021

nginx vulnerability
==========================================================================

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

- Ubuntu 21.04
- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

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:

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 21.04:
nginx 1.18.0-6ubuntu8.2
nginx-common 1.18.0-6ubuntu8.2
nginx-core 1.18.0-6ubuntu8.2
nginx-extras 1.18.0-6ubuntu8.2
nginx-full 1.18.0-6ubuntu8.2
nginx-light 1.18.0-6ubuntu8.2

Ubuntu 20.10:
nginx 1.18.0-6ubuntu2.2
nginx-common 1.18.0-6ubuntu2.2
nginx-core 1.18.0-6ubuntu2.2
nginx-extras 1.18.0-6ubuntu2.2
nginx-full 1.18.0-6ubuntu2.2
nginx-light 1.18.0-6ubuntu2.2

Ubuntu 20.04 LTS:
nginx 1.18.0-0ubuntu1.2
nginx-common 1.18.0-0ubuntu1.2
nginx-core 1.18.0-0ubuntu1.2
nginx-extras 1.18.0-0ubuntu1.2
nginx-full 1.18.0-0ubuntu1.2
nginx-light 1.18.0-0ubuntu1.2

Ubuntu 18.04 LTS:
nginx 1.14.0-0ubuntu1.9
nginx-common 1.14.0-0ubuntu1.9
nginx-core 1.14.0-0ubuntu1.9
nginx-extras 1.14.0-0ubuntu1.9
nginx-full 1.14.0-0ubuntu1.9
nginx-light 1.14.0-0ubuntu1.9

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

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

Package Information:
  https://launchpad.net/ubuntu/+source/nginx/1.18.0-6ubuntu8.2
  https://launchpad.net/ubuntu/+source/nginx/1.18.0-6ubuntu2.2
  https://launchpad.net/ubuntu/+source/nginx/1.18.0-0ubuntu1.2
  https://launchpad.net/ubuntu/+source/nginx/1.14.0-0ubuntu1.9