Security readout for executives and security teams
Plain-English summary
During Home Assistant’s initial setup, an internet-reachable attacker could upload a malicious backup that writes files outside the intended backup folder. This can alter the host, disrupt service, and become especially serious when Home Assistant runs as root. Versions before 2026.6.0 are affected.
Executive priority
Prioritize immediate remediation for pre-2026.6.0 systems that are onboarding, newly deployed, or reachable from untrusted networks. The unauthenticated arbitrary-write capability creates substantial integrity and availability risk, especially under root. Also investigate potentially exposed onboarding periods, while avoiding claims of compromise without supporting evidence.
Technical view
The backup upload path trusts the archive’s backup.json name field. An absolute path causes pathlib path joining to discard the configured backup-directory prefix, enabling unauthenticated arbitrary file writes during onboarding. Write scope follows process permissions; a root process provides full filesystem access. The issue is classified as CWE-22 with CVSS 9.3.
Likely exposure
Exposure requires Home Assistant Core before 2026.6.0 to be in its initial onboarding window with the backup-upload interface reachable by an attacker. Internet-exposed or untrusted-network deployments are the principal concern. Completed onboarding may reduce immediate reachability, but the supplied evidence does not establish whether other states expose the same path.
Exploitation context
The attack is remote, low complexity, unauthenticated, and requires no user interaction, but depends on the onboarding window. The supplied bundle marks this CVE as absent from KEV and provides no cited evidence of active exploitation. Treat practical exploitation status as unconfirmed.
Researcher notes
The security boundary failure occurs when an attacker-controlled absolute name is combined with the backup directory using pathlib.Path.__truediv__. Absolute-path semantics replace the intended prefix rather than remaining beneath it. The supplied materials identify a patch commit and pull request, but do not provide evidence of exploitation in the wild or documented compromise indicators.
Mitigation direction
- Upgrade Home Assistant Core to version 2026.6.0 or later.
- Restrict onboarding access to trusted networks until the upgrade is complete.
- Avoid running Home Assistant with root filesystem privileges where deployment architecture permits.
- Check current Home Assistant vendor guidance for any additional containment recommendations.
Validation and detection
- Confirm the installed Home Assistant Core version is 2026.6.0 or later.
- Determine whether onboarding or backup restoration was exposed to untrusted networks.
- Review onboarding-period backup upload activity for unexpected or unrecognized archives.
- Inspect the host for unexpected file creation or modification during the exposure window.
- Verify the Home Assistant process account and its effective filesystem permissions.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-64825 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L3.94.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L——VulnCheckVulnerability scoring details
Base CVSS 4.0 score
9CriticalVector: 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
Base CVSS 3.1 score
9.3CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Release NotesCVE reference, VulnCheck · release-notes
- Pull RequestCVE reference, VulnCheck · issue-tracking
- Patch CommitCVE reference, VulnCheck · patch
- https://www.vulncheck.com/advisories/home-assistant-core-path-traversal-file-write-via-backup-uploadCVE reference, VulnCheck · third-party-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.