Postfix Denial of Service Vulnerability in Ubuntu Releases

Severity: Medium (Score: 45.9)

Sources: Linuxsecurity, launchpad.net, Ubuntu

Summary

A denial of service vulnerability has been identified in Postfix, affecting multiple Ubuntu releases including 26.04 LTS, 25.10, 24.04 LTS, and 22.04 LTS. Discovered by Kamil Frankowicz, the flaw allows remote attackers to crash Postfix by sending specially crafted network traffic. The vulnerability is tracked as CVE-2026-43964, which was published on May 4, 2026. Users are advised to update their systems to the latest package versions to mitigate the risk. The affected versions include Postfix 3.10.6-4ubuntu2.1 for Ubuntu 26.04 LTS and earlier versions for other releases. A standard system update is recommended to address this issue. The vulnerability does not appear to be actively exploited at this time. Key Points: • Postfix vulnerability allows denial of service via crafted network traffic. • Affected Ubuntu versions include 26.04 LTS, 25.10, 24.04 LTS, and 22.04 LTS. • Users should update to the latest Postfix package versions to mitigate risks.

Key Entities

• DDoS (attack_type)
• Denial of Service (attack_type)
• CVE-2026-43964 (cve)
• Cwe-400 - Uncontrolled Resource Consumption (cwe)
• Postfix (platform)
• Ubuntu (company)