Which versions of Home Assistant Core are affected by CVE-2026-64825?

Home Assistant Core versions before 2026.6.0 contain a critical arbitrary file write vulnerability enabling unauthenticated attackers to achieve full host compromise through malicious backup archives…. A patch is available.

How to fix or mitigate CVE-2026-64825?

Within 24 hours, immediately upgrade all Home Assistant Core instances to version 2026.6.0 or later, prioritizing supervised and OS installations running with root privileges. Within 7 days, audit deployment logs for any backup operations during initial onboarding prior to patching, restrict network access to the onboarding interface to trusted networks, and verify patch deployment across the entire Home Assistant infrastructure. Within 30 days, implement file integrity monitoring on critical system directories and conduct a full security review of the initial onboarding procedures.

Home Assistant Core CVE-2026-64825

Q: What is the CVSS score of CVE-2026-64825?

CVE-2026-64825 has a CVSS 4.0 base score of 9.0 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.5%.

EUVD-2026-46301 CRITICAL

Path Traversal (CWE-22)

2026-07-21 VulnCheck

GHSA-5hxg-r395-fqxx

Path Traversal Home Assistant Home Assistant Core

9.0

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

9.0 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

7.5 HIGH

AC:H because exploitation is limited to the transient onboarding window; PR:N/UI:N as it is unauthenticated with no interaction; S:C and I:H for root-level arbitrary write escaping the app to the whole host, C:N as no read primitive.

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

4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Source Code Evidence Fetched

Jul 21, 2026 - 16:25 vuln.today

Analysis Generated

Jul 21, 2026 - 16:25 vuln.today

CVE Published

Jul 21, 2026 - 15:40 cve.org

CRITICAL 9.0

DescriptionCVE.org

Home Assistant Core before 2026.6.0 contains a path traversal vulnerability that allows unauthenticated attackers to write arbitrary files to any directory on the host filesystem by uploading a crafted backup archive during the initial onboarding window. Attackers can manipulate the 'name' field inside the uploaded archive's backup.json to supply an absolute path, causing pathlib.Path.__truediv__ to discard the configured backup directory prefix and write attacker-controlled content to arbitrary locations, with full filesystem access when the process runs as root.

AnalysisAI

Arbitrary file write in Home Assistant Core before 2026.6.0 lets unauthenticated attackers plant attacker-controlled files anywhere on the host by uploading a malicious backup archive during the initial onboarding window. Because the process frequently runs as root (e.g., in the supervised/OS install), this path traversal escalates to full host compromise. No public exploit is identified at time of analysis, and it is not listed in CISA KEV, but a vendor-released patch (2026.6.0) exists and the issue was reported by VulnCheck.

Technical ContextAI

Home Assistant Core is a Python-based open-source home automation platform. The flaw is a classic CWE-22 path traversal in the backup restore/upload path: the backup archive contains a backup.json whose 'name' field is used to construct the destination path via Python's pathlib. When an attacker supplies an absolute path in that field, pathlib.Path.__truediv__ (the '/' operator) discards the configured backup-directory prefix entirely - because joining a base path with an absolute path in pathlib returns the absolute path - so the intended sandbox directory is silently dropped and the file is written to the attacker-specified absolute location. The affected component per the NVD CPE is cpe:2.3:a:home-assistant:home_assistant_core, all versions prior to 2026.6.0.

RemediationAI

Vendor-released patch: upgrade to Home Assistant Core 2026.6.0 or later (release notes: https://github.com/home-assistant/core/releases/tag/2026.6.0; fix commit 567fe858289876b68b8162a77bd46e1e1af79752). Because exploitation is confined to the pre-account onboarding window, the most effective compensating control for unpatched systems is to never expose a fresh, un-onboarded instance to untrusted networks: complete onboarding and create the owner account on a trusted local network segment before any port-forwarding or reverse-proxy exposure, and restrict access to the onboarding/backup-upload endpoints (place the instance behind a VPN or firewall so only trusted hosts can reach it during setup). As a hardening measure, run Home Assistant as a non-root user where the deployment model allows, which limits an arbitrary write to files the service user can reach rather than the entire host (trade-off: the Home Assistant OS/supervised installs expect elevated privileges, so this is only practical for Core/container installs).