CVE-2026-4105
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA flaw was found in systemd. The systemd-machined service contains an Improper Access Control vulnerability due to insufficient validation of the class parameter in the RegisterMachine D-Bus (Desktop Bus) method. A local unprivileged user can exploit this by attempting to register a machine with a specific class value, which may leave behind a usable, attacker-controlled machine object. This allows the attacker to invoke methods on the privileged object, leading to the execution of arbitrary commands with root privileges on the host system.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA flaw in systemd-machined allows local unprivileged users to exploit improper access control in the RegisterMachine D-Bus method. By providing a specific class parameter value during machine registration, an attacker can leave behind a usable, attacker-controlled machine object that can invoke privileged methods, leading to arbitrary command execution with root privileges.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- High
- Privileges
- Low
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify systemd-machined is runningRun 'systemctl status systemd-machined' or check for the machined service processAffected if systemd-machined is active and running on the system
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Determine installed systemd versionRun 'systemd --version' and compare the version number to the fixed release that addresses this vulnerabilityAffected if the installed systemd version is older than the patched version containing the fix for CVE-2026-4105
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Check D-Bus policy for machine creationInspect /etc/dbus-1/system.d/org.freedesktop.machine1.conf or run 'busctl introspect org.freedesktop.machine1 /org/freedesktop/machine1' to review access control rulesAffected if unprivileged users have permission to call RegisterMachine without proper authorization restrictions
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List existing machine objectsRun 'machinectl list' to see currently registered machinesAffected if unexpected or attacker-controlled machine objects exist that were not created by legitimate administrators
The system is affected if systemd-machined is running and the installed systemd version predates the patch, or if unprivileged users can register machines via the D-Bus interface.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply the vendor patch for systemd that adds proper validation of the class parameter in the RegisterMachine D-Bus method to prevent unprivileged users from creating attacker-controlled machine objects.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4105 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-4105 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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