CVE-2026-64823: Home-Assistant Home Assistant Core

Medium severity, CVSS 4.7. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Home-Assistant Home Assistant Core: before 2026.5.4 (fixed in 2026.5.4)

Published 2026-07-21. Last modified 2026-07-22.