What is the CVSS score of CVE-2026-34205?

CVE-2026-34205 has a CVSS 3.1 base score of 9.6 (Critical). CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Docker are affected by CVE-2026-34205?

Home Assistant Supervisor versions prior to 2026.03.02 contain a critical network isolation bypass affecting Docker-based deployments on Linux, allowing any device on the local network to access…. A patch is available.

Is there a public PoC exploit available for CVE-2026-34205?

Yes, a public proof-of-concept exploit is available for CVE-2026-34205. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-34205?

Within 24 hours: Identify all Home Assistant Supervisor instances running versions prior to 2026.03.02 using network asset inventory or configuration management tools. Within 7 days: Update all affected Supervisor instances to version 2026.03.02 or later via official vendor channels; verify Docker host network mode configurations post-patch and disable where not operationally required. Within 30 days: Audit network segmentation for all Home Assistant deployments; restrict Layer 2 access to Home Assistant Docker hosts using VLAN isolation or network access controls; document and test failover procedures for any automation dependent on Supervisor connectivity.

Docker CVE-2026-34205

EUVD-2026-16793 CRITICAL

Improper Restriction of Communication Channel to Intended Endpoints (CWE-923)

2026-03-27 security-advisories@github.com

Docker Information Disclosure

9.6

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.6 CRITICAL

AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

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

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Updated

Apr 16, 2026 - 05:48 EUVD-patch-fix

executive_summary

Re-analysis Queued

Apr 16, 2026 - 05:29 backfill_euvd_patch

patch_released

Patch available

Apr 16, 2026 - 05:29 EUVD

2026.03.2

PoC Detected

Mar 30, 2026 - 13:26 vuln.today

Public exploit code

EUVD ID Assigned

Mar 27, 2026 - 20:22 euvd

EUVD-2026-16793

Analysis Generated

Mar 27, 2026 - 20:22 vuln.today

CVE Published

Mar 27, 2026 - 20:16 nvd

CRITICAL 9.6

DescriptionGitHub Advisory

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.

AnalysisAI

Unauthenticated network access to Home Assistant apps bypasses intended Docker isolation on Linux systems, exposing internal services to any device on the local network. Apps configured with host network mode inadvertently bind internal Docker bridge endpoints to the broader LAN without authentication controls, enabling unauthorized access with high confidentiality, integrity, and availability impact (CVSS 9.6). Vendor-released patch available in Home Assistant Supervisor 2026.03.02. No public exploit identified at time of analysis, though exploitation requires only adjacent network access with low attack complexity.

Technical ContextAI

Home Assistant is an open-source home automation platform emphasizing local control and privacy. The vulnerability stems from CWE-923 (Improper Restriction of Communication Channel to Intended Endpoints), specifically affecting the Docker networking configuration on Linux hosts. Apps (formerly called add-ons) using host network mode are intended to isolate services on the internal Docker bridge interface (typically docker0, 172.17.0.0/16 range). However, the configuration fails to properly restrict these endpoints, causing services that should only be accessible within the Docker network namespace to become reachable from any host on the same physical or virtual LAN. This misconfiguration exposes unauthenticated API endpoints, management interfaces, or service ports that lack authentication because they were designed to operate in a trusted internal context. The issue is specific to Linux implementations of Home Assistant Supervisor's Docker networking stack, where iptables rules or network namespace isolation do not adequately enforce the intended boundary between the Docker bridge and the external network interface.

RemediationAI

Upgrade Home Assistant Supervisor to version 2026.03.02 or later, which implements proper network isolation controls for apps using host network mode. The patch enforces iptables rules or network namespace boundaries to restrict Docker bridge interface endpoints to their intended scope, preventing LAN-wide exposure. Administrators should navigate to Settings > System > Updates in the Home Assistant web interface and apply the Supervisor update immediately. For systems unable to patch immediately, implement network-level mitigation by isolating the Home Assistant host on a dedicated VLAN or network segment with firewall rules permitting only necessary inbound connections from trusted management devices. Review all installed apps configured with host network mode and assess whether this configuration is required-switching to bridge mode (default) where feasible eliminates the attack surface entirely, though this may break functionality for apps requiring direct host network access. Conduct a security audit of exposed services using network scanning tools like nmap from an adjacent host to identify which endpoints became accessible pre-patch. Full remediation guidance and technical discussion available in the GitHub security advisory at https://github.com/home-assistant/core/security/advisories/GHSA-gh5m-4m97-c95h.