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Fencer Vulns
medium 6.4

CVE-2026-40226 json

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

published 2026-04-10 6 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-21400

cvss
6.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits
0
none known

Summary

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

Patch / fix

  • systemd systemd 260
  • systemd Debian 12 252.39-1~deb12u2
  • systemd Debian 13 257.13-1~deb13u1
  • systemd Debian 14 260~rc3-1

debian advisories DEBIAN-CVE-2026-40226

  • systemd Ubuntu 22.04 LTS 249.11-0ubuntu3.21
  • systemd Ubuntu 24.04 LTS 255.4-1ubuntu8.16
  • systemd Ubuntu 25.10 257.9-0ubuntu2.5

ubuntu advisories UBUNTU-CVE-2026-40226

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • systemd hummingbird 1 260.1-2.1.hum1
  • systemd-pam hummingbird 1 260.1-2.1.hum1
  • systemd-libs hummingbird 1 260.1-2.1.hum1
  • systemd-udev hummingbird 1 260.1-2.1.hum1
  • systemd-tests hummingbird 1 260.1-2.1.hum1
  • systemd-ukify hummingbird 1 260.1-2.1.hum1
  • systemd-shared hummingbird 1 260.1-2.1.hum1
  • systemd-networkd hummingbird 1 260.1-2.1.hum1

red hat advisories RHSA-2026:7299

  • systemd SLES 16.0, Linux Micro Extras 6.2, Linux Micro 6.2 +1 more 257.13-160000.4.1
  • systemd SLE Module for Package Hub 15 SP7, SLE Module for Basesystem 15 SP7 254.27-150600.4.71.2
  • systemd Linux Micro 6.1 254.27-slfo.1.1_5.1
  • systemd Linux Micro 6.0 254.27-4.1
  • systemd SLE Micro 5.5, SLE Micro 5.4, SLE Micro 5.3 249.17-150400.8.64.1
  • systemd SLE Micro 5.2 246.16-150300.7.74.1

suse advisories SUSE-SU-2026:23470-1SUSE-SU-2026:23620-1SUSE-SU-2026:23454-1SUSE-SU-2026:3244-1SUSE-SU-2026:22890-1SUSE-SU-2026:22736-1

  • systemd openSUSE Leap 16.0 257.13-160000.4.1
  • systemd-mini openSUSE Leap 16.0 257.13-160000.4.1

opensuse advisories openSUSE-SU-2026:21754-1

  • systemd Azure Linux 3.0 255-30

azure linux advisories AZL-82646

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-40226 updated cvss 6.4

systemd: systemd nspawn: Escape-to-host action via crafted config file

  • Red Hat Hardened Images systemd 260.1-2.1.hum1, systemd-pam 260.1-2.1.hum1, systemd-libs 260.1-2.1.hum1, systemd-udev 260.1-2.1.hum1, systemd-tests 260.1-2.1.hum1, systemd-ukify 260.1-2.1.hum1, +14 more
    fixed: vendor fix RHSA-2026:7299
  • Red Hat Enterprise Linux 7 systemd, libgudev1, systemd-libs, systemd-sysv, systemd-python, systemd-networkd, +2 more Red Hat Enterprise Linux 8 systemd, systemd-pam, systemd-libs, systemd-udev, systemd-tests, NetworkManager, +16 more Red Hat Enterprise Linux 9 systemd, systemd-pam, systemd-libs, systemd-oomd, systemd-udev, systemd-ukify, +21 more Red Hat Enterprise Linux 10 systemd, rpm-ostree, NetworkManager Red Hat OpenShift Container Platform 4 systemd, systemd-pam, systemd-libs, systemd-oomd, systemd-udev, systemd-tests, +24 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
6 mo ago

Exploit prediction

0.07% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.4 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected products

  • systemd systemd

Classification

Weakness
  • CWE-348 Use of Less Trusted Source

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.