CVE-2021-27952: Ecobee ECOBEE3 Lite Firmware

Critical severity, CVSS 9.8. EPSS: 1.1% chance of exploitation in the next 30 days.

Hardcoded default root credentials exist on the ecobee3 lite 4.5.81.200 device. This allows a threat actor to gain access to the password-protected bootloader environment through the serial console.

Affected products

• Ecobee ECOBEE3 Lite Firmware: version 4.5.81.200 only

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