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

USN-5765-1: PostgreSQL vulnerability

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Ubuntu Security Notice USN-5765-1
December 07, 2022

postgresql-9.5 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 ESM

Summary:

PostgreSQL could allow unintended access to network services.

Software Description:
- postgresql-9.5: Object-relational SQL database

Details:

Jacob Champion discovered that PostgreSQL incorrectly handled SSL
certificate verification and encryption. A remote attacker could possibly
use this issue to inject arbitrary SQL queries when a connection is first
established.

Update instructions:

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

Ubuntu 16.04 ESM:
postgresql-9.5 9.5.25-0ubuntu0.16.04.1+esm3

After a standard system update you need to restart PostgreSQL to make all the
necessary changes.

References:
  https://ubuntu.com/security/notices/USN-5765-1
CVE-2021-23222