Ubuntu 20.04 Postfix Critical Denial of Service USN-8253-2 CVE-2026-43964
ubuntu
June 5, 2026
Postfix could be made to crash if it received specially crafted network traffic.
Summary
Postfix could be made to crash if it received specially crafted network
traffic.
Software Description:
- postfix: High-performance mail transport agent
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.
Topics Covered
Update Instructions
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 20.04 LTS
postfix 3.4.13-0ubuntu1.4+esm1
Available with Ubuntu Pro
Ubuntu 18.04 LTS
postfix 3.3.0-1ubuntu0.4+esm4
Available with Ubuntu Pro
Ubuntu 16.04 LTS
postfix 3.1.0-3ubuntu0.4+esm4
Available with Ubuntu Pro
Ubuntu 14.04 LTS
postfix 2.11.0-1ubuntu1.2+esm4
Available with Ubuntu Pro
In general, a standard system update will make all the necessary changes.References
https://ubuntu.com/security/notices/USN-8253-2
https://ubuntu.com/security/notices/USN-8253-1
CVE-2026-43964
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Ubuntu Security Notice USN-8253-2
Topics Covered
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