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

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Summary

CVECVE-2026-44698
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-29 14:16:28 UTC
Updated2026-05-29 14:16:28 UTC
DescriptionHome 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.

Risk And Classification

Primary CVSS: v3.1 8.3 HIGH from [email protected]

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

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.3HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
3.1CNADECLARED8.3HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Home-assistant Core affected < 2026.4.4 Not specified
CNA Home Assistant Companion App IOS affected < 2026.4.1 Not specified
CNA Home Assistant Companion App Android affected < 2026.4.4 Not specified

References

ReferenceSourceLinkTags
github.com/home-assistant/core/security/advisories/GHSA-7jp2-p2fw-mgvf [email protected] github.com
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