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[USN-8253-1] Postfix vulnerability

Posted on 07 May 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8253-1
May 07, 2026

postfix vulnerability
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

Postfix could be made to crash if it received specially crafted network
traffic.

Software Description:
- postfix: High-performance mail transport agent

Details:

Kamil Frankowicz discovered that Postfix incorrectly handled certain
enhanced status codes. A remote attacker could possibly use this issue to
cause Postfix to crash, resulting in a denial of service.

Update instructions:

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

Ubuntu 26.04 LTS
postfix 3.10.6-4ubuntu2.1

Ubuntu 25.10
postfix 3.10.2-1ubuntu2.1

Ubuntu 24.04 LTS
postfix 3.8.6-1ubuntu0.1

Ubuntu 22.04 LTS
postfix 3.6.4-1ubuntu1.4

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8253-1
CVE-2026-43964

Package Information:
https://launchpad.net/ubuntu/+source/postfix/3.10.6-4ubuntu2.1
https://launchpad.net/ubuntu/+source/postfix/3.10.2-1ubuntu2.1
https://launchpad.net/ubuntu/+source/postfix/3.8.6-1ubuntu0.1
https://launchpad.net/ubuntu/+source/postfix/3.6.4-1ubuntu1.4

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