CVE-2026-64823
MediumCVSS 4.7Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
Home Assistant Core before 2026.5.4 contains a cross-site scripting vulnerability in the Shelly integration's `async_get_media_image()` method. Attackers controlling a Shelly device's thumb field can serve arbitrary HTML content via a data URI with `text/html` content type without validation against an image-only allowlist. This enables theft of session tokens and authenticated calls to sensitive endpoints like locks, alarms, and covers.
Risk Assessment
An attacker can steal Home Assistant user session tokens and perform unauthorized actions such as unlocking locks, disabling alarms, or controlling covers, posing a serious risk to physical security and data.
Recommendation
Upgrade Home Assistant Core to version 2026.5.4 or later, which contains the fix.
Other vulnerabilities in Home Assistant Core
See all- CVE-2026-64825Critical
Home Assistant Core before version 2026.6.0 contains a path traversal vulnerability that allows unauthenticated attackers to write arbitrary files to any directory on the host filesystem by uploading a crafted backup archive during the initial onboarding window. Attackers can manipulate the 'name' field inside the uploaded archive's backup.json to supply an absolute path, causing pathlib.Path.__truediv__ to discard the configured backup directory prefix and write attacker-controlled content to arbitrary locations, with full filesystem access when the process runs as root.
- CVE-2026-64824High
A path traversal vulnerability in the backup-restore function of Home Assistant Core before 2026.7.0 allows attackers to write files to arbitrary absolute filesystem paths by supplying a crafted tar archive with a SYMTYPE entry. Because the official Docker image runs the process as root, attackers can achieve remote code execution by overwriting auto-imported Python paths such as site-packages/sitecustomize.py.
Original NVD description (English source)
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.