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CWE-923Weakness · CWE-923

CVE-2026-34205

CRITICAL · 9.6 CVSS v3.1 Published 2026-03-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
No privileges Zero-click

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 · unedited
Home Assistant is open source home automation software that puts local control and privacy first. Home Assistant apps (formerly add-ons) configured with host network mode expose unauthenticated endpoints bound to the internal Docker bridge interface to the local network. On Linux, this configuration does not restrict access to the app as intended, allowing any device on the same network to reach these endpoints without authentication. Home Assistant Supervisor 2026.03.02 addresses the issue.

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 confidence

Home Assistant add-ons configured with Docker host network mode on Linux incorrectly expose unauthenticated API endpoints via the internal Docker bridge interface to the local network, bypassing intended access restrictions and allowing any device on the same network to reach these endpoints without authentication.

MitigationUpdate Home Assistant Supervisor to version 2026.03.02 or later to patch the network isolation bypass. Review add-on network configurations and consider using bridge networking mode instead of host mode where feasible.

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check Home Assistant Supervisor version
    In Home Assistant, go to Settings > System > Repairs, or access the supervisor panel and note the Supervisor version number displayed
    Affected if The installed Supervisor version is earlier than 2026.03.02 (the patched version)
  2. Identify add-ons using host network mode
    Run 'docker ps --format "{{.Names}} {{.NetworkMode}}"' on the Home Assistant host to list containers and their network modes; look for entries showing 'host' as the NetworkMode
    Affected if Any add-on container displays 'host' as its NetworkMode, indicating it uses Docker host networking
  3. Verify Docker bridge interface exposure
    Run 'ip addr show docker0' or 'ip link show docker0' to confirm the docker0 bridge interface exists and is active on the host
    Affected if The docker0 bridge interface exists and is up, which is required for the bypass to be exploitable
  4. Test local network access to bridge IP
    From another device on the same local network, attempt to access the Docker bridge IP (typically 172.17.0.1) on common add-on ports (such as port 80, 443, or any port used by your add-ons); if connections succeed without authentication, the condition is met
    Affected if HTTP/HTTPS requests to 172.17.0.1 (or the Docker bridge IP) from another network device successfully reach add-on services without requiring authentication

You are affected if your Home Assistant Supervisor version is earlier than 2026.03.02 AND you have add-ons configured with Docker host network mode, allowing unauthenticated access via the Docker bridge interface from other devices on your local network.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update Home Assistant Supervisor to version 2026.03.02 or later to patch the network isolation bypass. Review add-on network configurations and consider using bridge networking mode instead of host mode where feasible.

Recommended fix Moderate confidence

Home Assistant Supervisor 2026.03.02

  1. Back up your Home Assistant configuration before performing any updates
  2. Open the Home Assistant web interface (Frontend)
  3. Navigate to Settings → System → Supervisor
  4. Click on the Supervisor card to access supervisor settings
  5. Look for an option to check for updates or update the supervisor
  6. If an update is available, apply the update to upgrade to Home Assistant Supervisor 2026.03.02
  7. Wait for the update to complete and verify the supervisor is running the new version
  8. Alternatively, access the Home Assistant CLI and run: ha supervisor update
Caveat Review any custom configurations or add-ons that may have dependencies on the previous supervisor version

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-34205 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data