USN-6591-2: Postfix update

Releases

• Ubuntu 23.10
• Ubuntu 22.04 LTS
• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM
• Ubuntu 16.04 ESM
• Ubuntu 14.04 ESM

Packages

• postfix - High-performance mail transport agent

Details

USN-6591-1 fixed vulnerabilities in Postfix. A fix with less risk of
regression has been made available since the last update. This update
updates the fix and aligns with the latest configuration guidelines
regarding this vulnerability.

We apologize for the inconvenience.

Original advisory 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 at https://www.postfix.org/smtp-smuggling.html.

Update instructions

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

Ubuntu 23.10

• postfix - 3.8.1-2ubuntu0.2

Ubuntu 22.04

• postfix - 3.6.4-1ubuntu1.3

Ubuntu 20.04

• postfix - 3.4.13-0ubuntu1.4

Ubuntu 18.04

• postfix - 3.3.0-1ubuntu0.4+esm3
  Available with Ubuntu Pro

Ubuntu 16.04

• postfix - 3.1.0-3ubuntu0.4+esm3
  Available with Ubuntu Pro

Ubuntu 14.04

• postfix - 2.11.0-1ubuntu1.2+esm3
  Available with Ubuntu Pro

After a standard system update, you need to set
"smtpd_forbid_bare_newline = normalize" in your configuration and reload
it to make all the necessary changes.

References

• CVE-2023-51764
• https://bugs.launchpad.net/ubuntu/+source/postfix/+bug/2049337
• https://bugs.launchpad.net/ubuntu/+source/postfix/+bug/2050834

Related notices

• USN-6591-1: postfix-ldap, postfix, postfix-doc, postfix-pgsql, postfix-lmdb, postfix-sqlite, postfix-pcre, postfix-cdb, postfix-mysql, postfix-dev