CVE-2026-64823
Home Assistant Core < 2026.5.4 XSS via Shelly media_player.py thumb URI
- State
- Published
- Severity
- 2.1 Low
- Published
- Jul 21, 2026
- Updated
- Jul 22, 2026
- Reserved
- Jul 20, 2026
Description
Home Assistant Core before 2026.5.4 contains a cross-site scripting vulnerability in the Shelly integration's async_get_media_image() method that allows attackers controlling a Shelly device's thumb field to serve arbitrary HTML content by supplying a data URI with a text/html content type without validation against an image-only allowlist. Attackers can cause the media player proxy endpoint to serve attacker-controlled bytes with Content-Type text/html in the Home Assistant web origin, enabling theft of session tokens from local storage and authenticated calls to sensitive service endpoints including lock, alarm, and cover controls.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 2.1 Low | CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N | VulnCheck |
| 3.1 | 4.7 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N | VulnCheck |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
Home Assistant Corehome-assistant |
|
References
- Release Notesrelease-notes
- Pull Requestissue-tracking
- Patch Commitpatch
- https://www.vulncheck.com/advisories/home-assistant-core-xss-via-shelly-media-player-py-thumb-urithird-party-advisory
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