{"id":"CVE-2026-64823","title":"Home Assistant Core < 2026.5.4 XSS via Shelly media_player.py thumb URI","summary":"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 …","severity":"medium","cvss":4.7,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N","cvssSource":"cna","cwe":["CWE-79"],"vendor":"home-assistant","product":"Home Assistant Core","affected":["home_assistant_core < 2026.5.4"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-07-22T14:12:03.484754Z"},"published":"2026-07-21","updated":"2026-11-08","sourceUpdated":"2026-11-08T14:07:59.946Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64823","references":[{"url":"https://github.com/home-assistant/core/releases/tag/2026.5.4","label":"Home Assistant Core 2026.5.4 Release Notes"},{"url":"https://github.com/home-assistant/core/pull/171585","label":"Pull Request"},{"url":"https://github.com/home-assistant/core/commit/894a68acb678afc382fe5ea9002e61ab7f862011","label":"Patch Commit"},{"url":"https://www.vulncheck.com/advisories/home-assistant-core-xss-via-shelly-media-player-py-thumb-uri"}],"tags":["cve.org"],"epss":0.00296,"epssPercentile":0.22369,"ingestedAt":"2026-11-08T14:51:22.269Z","slug":"CVE-2026-64823","body":"## Overview\n\nHome 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.\n\n## Affected\n\n- `home_assistant_core < 2026.5.4`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":26,"depthScoreParts":{"impact":25.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}