What is CVE-2026-40226?

CVE-2026-40226 is a security advisory published by Microsoft Security Response Center (MSRC) with Medium severity. In nspawn in systemd 233 through 259 before 260, an escape-to-host action can occur via a crafted optional config file.

Which CVE IDs does CVE-2026-40226 cover?

CVE-2026-40226 covers the following CVE IDs: CVE-2026-40226. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-40226?

CVE-2026-40226 has a CVSS v3 base score of 6.4, published by Microsoft Security Response Center (MSRC).

Which products are affected by CVE-2026-40226?

CVE-2026-40226 affects 5 products, including: azl3 systemd 255-26 on Azure Linux 3.0; azl3 systemd 255-27 on Azure Linux 3.0; azl3 systemd 255-30 on Azure Linux 3.0; cbl2 systemd 250.3-24 on CBL Mariner 2.0; cbl2 systemd 250.3-24 on CBL-Mariner 2.0.

CVE-2026-40226MediumCVSS 6.4

In nspawn in systemd 233 through 259 before 260, an escape-to-host action can occur via a crafted optional config file.

Vendor

Microsoft Security Response Center (MSRC)

Published

June 2, 2026

Last Modified

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🔗 CVE IDs covered (1)

CVE-2026-40226 →

🎯 Affected products5

azl3 systemd 255-26 on Azure Linux 3.0
azl3 systemd 255-27 on Azure Linux 3.0
azl3 systemd 255-30 on Azure Linux 3.0
cbl2 systemd 250.3-24 on CBL Mariner 2.0
cbl2 systemd 250.3-24 on CBL-Mariner 2.0

✅ Remediation

KBCBL-Mariner Releases (Security Update) — fixed build 255-28 KBCBL-Mariner Releases (Security Update) — fixed build 255-30 KBRelease Notes (Security Update)

🔗 References (2)

advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40226
referencehttps://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade