CVE-2026-64823
mediumpriority · track · 0EPSS 0.003 · 22 %ileEUEPSS · scored 2026-10-27
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
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 0.5–4.7
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (1)
Products and version ranges known to be affected.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (13)
External citations — patches, advisories, analysis.
- https://github.com/home-assistant/core/commit/894a68acb678afc382fe5ea9002e61ab7f862011cnnvd
- https://github.com/home-assistant/core/pull/171585cnnvd
- https://github.com/home-assistant/core/releases/Patchcnnvd
- https://github.com/home-assistant/core/releases/tag/2026.5.4cnnvd
- https://www.vulncheck.com/advisories/home-assistant-core-xss-via-shelly-media-player-py-thumb-uricnnvd
- https://github.com/home-assistant/core/commit/894a68acb678afc382fe5ea9002e61ab7f862011enisa_euvd
- https://github.com/home-assistant/core/pull/171585enisa_euvd
- https://github.com/home-assistant/core/releases/tag/2026.5.4enisa_euvd
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