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CVE-2021-41104

24
FAUCET Score

CVE-2021-41104 affects ESPHome versions 2021.9.1 and older, specifically when the web_server is enabled with HTTP basic authentication. The vulnerability allows unauthenticated over-the-air (OTA) updates, bypassing the configured basic authentication for ESP8266/ESP32 devices. Rated 7.5 HIGH on the CVSS scale, this vulnerability is easily exploitable over the network without user interaction (AV:N/AC:L/PR:N/UI:N), leading to high integrity impact (I:H) as unauthorized firmware can be installed. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 2021.9.2CPE matchmatch criteria
cpe:2.3:o:esphome:esphome_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.21%
Probability of exploitation in next 30 days
EPSS Percentile
65.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0121 is in the 44th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: esphomeFixed in: 2021.9.2

Vendor Advisories (1)

pipGHSA-48mj-p7x2-5jfmhigh

Basic auth bypass in esphome

Sep 29, 2021

References

github.com / esphome/esphome/pull/2409/commits/207cde1667d8c799a197b78ca8a5a14de8d5ca1e
PatchThird Party Advisory
github.com / esphome/esphome/releases/tag/2021.9.2
Release NotesThird Party Advisory
github.com / esphome/esphome/security/advisories/GHSA-48mj-p7x2-5jfm
PatchThird Party Advisory