CVE-2025-57808 – esphome

Package

Manager: pip
Name: esphome
Vulnerable Version: >=0 <2025.8.1

Severity

Level: High

CVSS v3.1: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v4.0: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS: 0.00024 pctl0.04871

Details

ESP-IDF web_server basic auth bypass using empty or incomplete Authorization header ### Summary On the ESP-IDF platform, ESPHome's [`web_server` authentication](https://esphome.io/components/web_server.html#configuration-variables) check can pass incorrectly when the client-supplied base64-encoded `Authorization` value is empty or is a substring of the correct value (e.g., correct username with partial password). This allows access to `web_server` functionality (including OTA, if enabled) without knowing any information about the correct username or password. ### Details The HTTP basic auth check in `web_server_idf`'s [`AsyncWebServerRequest::authenticate`](https://github.com/esphome/esphome/blob/ef2121a215890d46dc1d25ad363611ecadc9e25e/esphome/components/web_server_idf/web_server_idf.cpp#L256) only compares up to `auth.value().size() - auth_prefix_len` bytes of the base64-encoded `user:pass` string. This means a client-provided valuer like `dXNlcjpz` (`user:s`) will pass the check when the correct value is much longer, e.g., `dXNlcjpzb21lcmVhbGx5bG9uZ3Bhc3M=` (`user:somereallylongpass`). Furthermore, the check will also pass when the supplied value is the empty string, which removes the need to know (or brute force) the username. A browser won't generally issue such a request, but it can easily be done by manually constructing the `Authorizaztion` request header (e.g., via `curl`). ### PoC Configure ESPHome as follows: ```yaml esp32: board: ... framework: type: esp-idf web_server: auth: username: user password: somereallylongpass ``` In a browser, you can correctly log in by supplying username `user` and password `somereallylongpass`... but you can _also_ incorrectly log in by supplying _substrings_ of the password whose base64-encoded digest matches a _prefix_ of the correct digest. (For example, I was able to log into an ESPHome device so configured by supplying password `some`... or even just `s`.) You can also use a tool like `curl` to manually set an `Authorization` request header that _always_ passes the check without any knowledge of the username: ``` $ curl -D- http://example.local/ HTTP/1.1 401 Unauthorized ... $ curl -D- -H 'Authorization: Basic ' http://example.local/ HTTP/1.1 200 OK ... ``` ### Impact This vulnerability effectively nullifies basic auth support for the ESP-IDF `web_server`, allowing auth bypass from another device on the local network with no knowledge of the correct username or password required. ### Remediation This vulnerability is fixed in 2025.8.1 and later. For older versions, disabling the `web_server` component on ESP-IDF devices may be prudent, particularly if OTA updates through `web_server` are enabled.

Metadata

Created: 2025-09-02T16:46:58Z
Modified: 2025-09-02T16:46:58Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/09/GHSA-mxh2-ccgj-8635/GHSA-mxh2-ccgj-8635.json
CWE IDs: ["CWE-187", "CWE-303"]
Alternative ID: GHSA-mxh2-ccgj-8635
Finding: F115
Auto approve: 1