USN-6591-1: Postfix vulnerability

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

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 - 3.8.1-2ubuntu0.1

Ubuntu 22.04

• postfix - 3.6.4-1ubuntu1.2

Ubuntu 20.04

• postfix - 3.4.13-0ubuntu1.3

Ubuntu 18.04

• postfix - 3.3.0-1ubuntu0.4+esm2
  Available with Ubuntu Pro

Ubuntu 16.04

• postfix - 3.1.0-3ubuntu0.4+esm2
  Available with Ubuntu Pro

Ubuntu 14.04

• postfix - 2.11.0-1ubuntu1.2+esm2
  Available with Ubuntu Pro

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.

References

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

Related notices

• USN-6591-2: postfix-ldap, postfix-mysql, postfix-doc, postfix-sqlite, postfix-pcre, postfix-lmdb, postfix-cdb, postfix-pgsql, postfix, postfix-dev