CVE-2025-25305

EUVD-2025-4771 · Published Feb 18, 2025

Home Assistant does not correctly validate SSL for outgoing requests in core and used libs

Summary

Problem: Potential man-in-the-middle attacks due to missing SSL certificate verification in the project codebase and used third-party libraries.

Details

In the past, aiohttp-session/request had the parameter verify_ssl to control SSL certificate verification. This was a boolean value. In aiohttp 3.0, this parameter was deprecated in favor of the ssl parameter. Only when ssl is set to None or provided with a correct configured SSL context the standard SSL certificate verification will happen.

When migrating integrations in Home Assistant and libraries used by Home Assistant, in some cases the verify_ssl parameter value was just moved to the new ssl parameter. This resulted in these integrations and 3rd party libraries using request.ssl = True, which unintentionally turned off SSL certificate verification and opened up a man-in-the-middle attack vector.

Example:
https://github.com/home-assistant/core/blob/c4411914c2e906105b765c00af5740bd0880e946/homeassistant/components/discord/notify.py#L84

When you scan the libraries used by the integrations in Home Assistant, you will find more issues like this.

The general handling in Home Assistant looks good, as homeassistant.helpers.aoihttp_client._async_get_connector handles it correctly.

PoC

Check that expired.badssl.com:443 gives an SSL error in when connecting with curl or browser.
Add the integration adguard with the setting host=expired.badssl.com, port=443, use-ssl=true, verify-ssl=true.
Check the logs - you get a HTTP 403 response.

Expected behavior:

The integration log shows an ssl.SSLCertVerificationError.

The following code shows the problem with ssl=True. No exception is raised when ssl=True (Python 3.11.6).

import asyncio
from ssl import SSLCertVerificationError

import aiohttp

BAD_URL = "https://expired.badssl.com/"


async def run_request(verify_ssl, result_placeholder: str):
    async with aiohttp.ClientSession() as session:
        exception_fired: bool = False
        try:
            await session.request("OPTIONS", BAD_URL, ssl=verify_ssl)
        except SSLCertVerificationError:
            exception_fired = True
        except Exception as error:
            print(error)
        else:
            exception_fired = False
        print(result_placeholder.format(exception_result=exception_fired))


# Case 1: ssl=False --> expected result: No exception
asyncio.run(run_request(False, "Test case 1: expected result: False - result: {exception_result}"))

# Case 2: ssl=None --> expected result: Exception
asyncio.run(run_request(None, "Test case 2: expected result: True - result: {exception_result}"))

# Case 3: ssl=True --> expected result: No Exception
asyncio.run(run_request(True, "Test case 3: expected result: False - result: {exception_result}"))

Technologies

Homeassistant Homeassistant

Weaknesses

CWE-940CWE-347

CVSS scores

v3.17.0CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:L

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

Criticalyesterday

Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Two situations are possible. When the decoding is done by your own application or reverse proxy, identify the component and update it. If an update is not possible right away, reject requests with "Content-Encoding: br" at the reverse proxy or WAF. When the asset is hosted on a managed platform or behind a CDN (for example Platform.sh, Upsun or Fastly), the decoding may be done by the provider's edge router, in front of your application. You cannot patch it yourself, but this router handles all the traffic of your site. Ask your provider to confirm that its edge components are patched against CVE-2026-111497. Assets hosted on a managed platform or behind a CDN carry the tag "paas: platform.sh" or "cdn: fastly" in the asset view: for these assets, the Brotli decoding is done by the provider's edge router, in front of your application, and only the provider can patch it. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Contact your edge provider about the status of the pathing (Fastly / Plateform.sh) Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.