CVE-2021-41104: Esphome Firmware

High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days.

ESPHome is a system to control the ESP8266/ESP32. Anyone with web_server enabled and HTTP basic auth configured on version 2021.9.1 or older is vulnerable to an issue in which `web_server` allows over-the-air (OTA) updates without checking user defined basic auth username & password. This issue is patched in version 2021.9.2. As a workaround, one may disable or remove `web_server`.

Affected products

• Esphome Esphome Firmware: before 2021.9.2 (fixed in 2021.9.2)

Published 2021-09-28. Last modified 2026-06-17.