CVE-2021-27954: Ecobee ECOBEE3 Lite Firmware

High severity, CVSS 8.2. EPSS: 0.9% chance of exploitation in the next 30 days.

A heap-based buffer overflow vulnerability exists on the ecobee3 lite 4.5.81.200 device in the HKProcessConfig function of the HomeKit Wireless Access Control setup process. A threat actor can exploit this vulnerability to force the device to connect to a SSID or cause a denial of service.

Affected products

• Ecobee ECOBEE3 Lite Firmware: version 4.5.81.200 only

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