Ubuntu 23.10 USN-6591-1 Moderate: Postfix Email Auth Bypass

ubuntu

January 22, 2024

Postfix could allow bypass of email authentication if it received specially crafted network traffic.

Summary

Postfix could allow bypass of email authentication if it received

specially crafted network traffic.

Software Description:

- postfix: High-performance mail transport agent

Details:

Timo Longin discovered that Postfix incorrectly handled certain email line

endings. A remote attacker could possibly use this issue to bypass an email

authentication mechanism, allowing domain spoofing and potential spamming.

Please note that certain configuration changes are required to address

this issue. They are not enabled by default for backward compatibility.

Information can be found athttps://www.postfix.org/smtp-smuggling.html.

Topics Covered

security advisory moderate Ubuntu postfix email authentication domain spoofing

Update Instructions

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

Ubuntu 23.10:
   postfix                         3.8.1-2ubuntu0.1

Ubuntu 22.04 LTS:
   postfix                         3.6.4-1ubuntu1.2

Ubuntu 20.04 LTS:
   postfix                         3.4.13-0ubuntu1.3

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
   postfix                         3.3.0-1ubuntu0.4+esm2

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   postfix                         3.1.0-3ubuntu0.4+esm2

Ubuntu 14.04 LTS (Available with Ubuntu Pro):
   postfix                         2.11.0-1ubuntu1.2+esm2

After a standard system update you need to enable
smtpd_forbid_bare_newline in your configuration and reload it to make
all the necessary changes.