Vulnerability 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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/home-assistant/core/commit/894a68acb678afc382fe5ea9002e61ab7f
- https://github.com/home-assistant/core/pull/171585
- https://github.com/home-assistant/core/releases/tag/2026.5.4
- https://www.vulncheck.com/advisories/home-assistant-core-xss-via-shelly-media-pl
FAQ
What is CVE-2026-64823?
CVE-2026-64823 is a vulnerability with a CVSS score of 4.7 (MEDIUM). 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 f...
How severe is CVE-2026-64823?
CVE-2026-64823 has been rated MEDIUM with a CVSS base score of 4.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-64823?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.