CVE-2021-41104
HIGHESPHome 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`…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Description
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2021-41104 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-41104 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-41104. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-41104 in your dependencies?
O3 detects CVE-2021-41104 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.