Ubuntu USN · USN-8253-2

Postfix vulnerability

Published: Wed, 03 Jun 2026 20:22

CVE-2026-43964

Summary

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

Details

USN-8253-1 fixed a vulnerability in Postfix. This update provides the corresponding fix for Postfix on Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. Original advisory 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.

Recommended actions per Ubuntu release

StackPatch playbook auto-generated per release codename and per affected package.

Ubuntu bionic

postfix→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-cdb→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-cdb
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-doc→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-doc
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-ldap→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-ldap
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-lmdb→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-lmdb
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-mysql→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-mysql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pcre→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pcre
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pgsql→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pgsql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-sqlite→3.3.0-1ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.3.0-1ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-sqlite
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu focal

postfix→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-cdb→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-cdb
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-doc→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-doc
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-ldap→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-ldap
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-lmdb→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-lmdb
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-mysql→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-mysql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pcre→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pcre
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pgsql→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pgsql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-sqlite→3.4.13-0ubuntu1.4+esm1apt_upgrade
Standard apt upgrade. Install 3.4.13-0ubuntu1.4+esm1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-sqlite
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu trusty

postfix→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-cdb→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-cdb
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-dev→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-dev
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-doc→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-doc
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-ldap→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-ldap
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-mysql→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-mysql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pcre→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pcre
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pgsql→2.11.0-1ubuntu1.2+esm4apt_upgrade
Standard apt upgrade. Install 2.11.0-1ubuntu1.2+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pgsql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu xenial

postfix→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-cdb→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-cdb
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-dev→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-dev
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-doc→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-doc
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-ldap→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-ldap
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-mysql→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-mysql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pcre→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pcre
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
postfix-pgsql→3.1.0-3ubuntu0.4+esm4apt_upgrade
Standard apt upgrade. Install 3.1.0-3ubuntu0.4+esm4 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y postfix-pgsql
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Are YOU affected by USN-8253-2?

5-second check on your actual server. Reads /etc/os-release, uname -r, and dpkg-query; matches against the live USN + Debian Security Tracker feeds; tells you whether USN-8253-2 (and any other live CVE) applies. Anonymous, no signup.

curl https://mindsparkstack.com/scan.sh | bash

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