=========================================================================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