CVE-2026-44698 PUBLISHED

Home Assistant: Cross-origin iframe access token exfiltration via WebView JS bridge callback injection

Assigner: GitHub_M
Reserved: 07.05.2026 Published: 29.05.2026 Updated: 29.05.2026

Home Assistant is open source home automation software that puts local control and privacy first. Prior to 2026.4.1 for iOS and 2026.4.4 for Android, he Home Assistant Companion apps for Android and iOS expose a JavaScript bridge to the in-app WebView window.externalApp on Android and webkit.messageHandlers.getExternalAuth (alongside revokeExternalAuth and externalBus) on iOS. Two flaws expose the bridge to all frames (including cross-origin iframes) and unsanitized interpolation of the JavaScript callback identifier allows a cross-origin iframe rendered inside the Companion app to execute arbitrary JavaScript in the Home Assistant frontend's main-frame origin and exfiltrate the signed-in user's access token. This vulnerability is fixed in 2026.4.1 for iOS and 2026.4.4 for Android.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
CVSS Score: 8.3

Product Status

Vendor home-assistant
Product core
Versions
  • Version < 2026.4.4 is affected
Vendor Home Assistant
Product Companion app (iOS)
Versions
  • Version < 2026.4.1 is affected
Vendor Home Assistant
Product Companion app (Android)
Versions
  • Version < 2026.4.4 is affected

References

Problem Types

  • CWE-94: Improper Control of Generation of Code ('Code Injection') CWE
  • CWE-346: Origin Validation Error CWE
  • CWE-749: Exposed Dangerous Method or Function CWE
  • CWE-940: Improper Verification of Source of a Communication Channel CWE