CVE-2021-27953: Ecobee ECOBEE3 Lite Firmware

High severity, CVSS 7.5. EPSS: 1.7% chance of exploitation in the next 30 days.

A NULL pointer dereference vulnerability exists on the ecobee3 lite 4.5.81.200 device in the HomeKit Wireless Access Control setup process. A threat actor can exploit this vulnerability to cause a denial of service, forcing the device to reboot via a crafted HTTP request.

Affected products

• Ecobee ECOBEE3 Lite Firmware: version 4.5.81.200 only

Published 2021-08-03. Last modified 2026-06-17.