CVE-2026-40223
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 · uneditedIn systemd 258 before 260, a local unprivileged user can trigger an assert when a Delegate=yes and User=<unset> unit exists and is running.
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 · moderate confidenceA local unprivileged user can trigger an assertion failure in systemd versions 258 through 259 when a service unit with Delegate=yes and User=<unset> is running. This causes systemd to crash due to an unhandled assertion, creating a denial-of-service condition.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 258, < 260CVSS 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
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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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Check installed systemd versionRun `systemctl --version` or `systemd --version` to determine the systemd version numberAffected if Version is 258 or 259 (versions 260 and later are not affected)
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Identify units with Delegate=yesSearch unit files in /etc/systemd/system/, /usr/lib/systemd/system/, and ~/.config/systemd/ for lines containing `Delegate=yes` using `grep -r "Delegate=yes"`Affected if Any .service file contains Delegate=yes without an accompanying User= setting
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Check for User= setting in Delegate unitsFor each unit with Delegate=yes, inspect the file and verify whether User= is explicitly set (look for User=<username> or User=root)Affected if Delegate=yes is present but User= is not defined in the same unit file
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Identify running affected servicesRun `systemctl list-units --type=service --state=running` and cross-reference with units found in steps 2-3 to identify currently running services with Delegate=yes and no User= setAffected if Any service matching the Delegate=yes without User= configuration is currently running
Environment is affected if systemd version is 258 or 259 AND at least one service unit with Delegate=yes and no User= setting is running.
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.
dbcve · scoped260
Upgrade systemd to version 260 or later, and avoid using Delegate=yes without setting an explicit User= in systemd unit files.
systemd 260
- Check current systemd version with: systemctl --version or hostnamectl
- Upgrade systemd to version 260 or later using your distribution's package manager (e.g., apt-get update && apt-get install systemd, yum update systemd, or dnf update systemd)
- After upgrading, reboot the system to ensure the new systemd init system is running
- Verify the fix by running: systemctl --version and confirming the version is >= 260
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40223 — 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-2026-40223 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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- Version or environment caveats, and links to real fixes
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