Summary
Patch released in 2021.9.2
Workarounds
Disable/remove web_server
Impact
Anyone with web_server enabled and HTTP basic auth configured on 2021.9.1 or older
web_server allows OTA update without checking user defined basic auth username & password
A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.
CVE-2021-41104 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2021.9.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2021-41104? CVE-2021-41104 is a high-severity missing authentication for critical function vulnerability in esphome (pip), affecting versions < 2021.9.2. It is fixed in 2021.9.2. A critical operation is accessible without requiring any authentication.
- How severe is CVE-2021-41104? CVE-2021-41104 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of esphome are affected by CVE-2021-41104? esphome (pip) versions < 2021.9.2 is affected.
- Is there a fix for CVE-2021-41104? Yes. CVE-2021-41104 is fixed in 2021.9.2. Upgrade to this version or later.
- Is CVE-2021-41104 exploitable, and should I be worried? Whether CVE-2021-41104 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2021-41104 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2021-41104? Upgrade
esphometo 2021.9.2 or later.