Description

Home Assistant is open source home automation software focused on local control and privacy. Prior to 2026.5.0, the iOS Companion app treats tag links (NFC or QR) delivered through an OS-level routing mechanism such as iOS universal links as if they were physically scanned, without validating the calling app or prompting the user. As a result, any untrusted app on the device can forward an arbitrary tag to Home Assistant, causing it to execute the associated automation as though a legitimate user had scanned an authorized tag. This allows silent, unattended automation execution by untrusted local callers. This issue has been fixed in version 2026.5.0.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-08-07T21:17:29.693Z",
  "pubdate": "2026-08-07T21:17:29.693Z",
  "executiveSummary": "An improper input validation vulnerability exists in the Home Assistant iOS Companion app prior to version 2026.5.0.\nThe vulnerability allows untrusted local applications on an iOS device to interact with OS-level routing mechanisms, specifically iOS universal links, to deliver arbitrary tag links (NFC or QR) to the application.\nThe core impact is the unauthorized, silent, and unattended execution of home automation scripts and routines without requiring user interaction or verifying the authenticity of the calling application.\nThe affected system is the Home Assistant iOS Companion app running on versions prior to 2026.5.0.\nThe risk implications involve local privilege abuse where malicious or compromised applications installed on the same device can manipulate smart home physical security and automation states.\nAttacker capabilities are restricted to local execution, requiring an untrusted app to be present on the target device.\nNo special privileges or authentication are enforced by the vulnerable routing mechanism during the IPC-like delegation of universal links.",
  "technicalDetails": "The root cause of the vulnerability lies in the improper handling and lack of validation of incoming OS-level routing mechanisms within the Home Assistant iOS Companion app prior to version 2026.5.0.\nSpecifically, the application processes tag links, such as NFC or QR codes, delivered via iOS universal links without validating the identity or provenance of the calling application.\nThe vulnerable component is the URI/Universal Link handling mechanism responsible for processing physical interaction triggers within the iOS application.\nThe application automatically trusts incoming routing payloads, treating them as if they originated from a genuine physical scan performed directly by the user.\nThe attack flow proceeds as follows: First, an adversary installs or leverages an untrusted local application on the victim's iOS device. Second, the malicious local app constructs a crafted iOS universal link containing an arbitrary tag payload. Third, the malicious app invokes the OS-level routing mechanism to forward the universal link to the Home Assistant iOS Companion app. Fourth, the Home Assistant app receives the routing request, fails to validate the calling context, and assumes a legitimate physical scan occurred. Finally, the application triggers the associated automation sequence mapped to the supplied tag, resulting in silent and unattended execution.\nAuthentication requirements are absent, as the application implicitly trusts local IPC-style invocations via universal links. Privilege requirements are minimal, requiring only the ability to execute an untrusted application locally on the device. Network exposure is localized to the client device operating system routing layer.\nThe payload behavior forces the Home Assistant backend to evaluate and execute pre-configured automations tied to specific tag identifiers, potentially compromising physical security, smart locks, lighting, or environmental controls managed by the Home Assistant instance."
}