Unauthenticated arbitrary file write via backup upload
Published Jul 21, 2026 · Updated Jul 21, 2026
Path traversal in Home Assistant Core before 2026.6.0 allows remote attackers to write arbitrary host files through a crafted backup upload. The backup reader trusts the name field in backup.json, and pathlib path joining treats an absolute value as a replacement for the configured backup directory. The unauthenticated upload route is reachable only during initial onboarding; successful writes inherit the Core process permissions, including full host filesystem access when it runs as root.
Summary
What happened
Path traversal in Home Assistant Core before 2026.6.0 allows remote attackers to write arbitrary host files through a crafted backup upload. The backup reader trusts the name field in backup.json, and pathlib path joining treats an absolute value as a replacement for the configured backup directory. The unauthenticated upload route is reachable only during initial onboarding; successful writes inherit the Core process permissions, including full host filesystem access when it runs as root.
The record
- CVE
- CVE-2026-64825
- Published
- Jul 21, 2026
- Updated
- Jul 21, 2026
- Vendor
- Home Assistant
- Product
- Home Assistant Core
- Classifications
- CWE-22, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 21, 2026CVE publishedPublication date reported by the CVE source.
- Jul 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <2026.6.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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