CVE-2023-41899 in Home Assistant
Summary
by MITRE • 10/25/2023
Home assistant is an open source home automation. In affected versions the `hassio.addon_stdin` is vulnerable to a partial Server-Side Request Forgery where an attacker capable of calling this service (e.g.: through GHSA-h2jp-7grc-9xpp) may be able to invoke any Supervisor REST API endpoints with a POST request. An attacker able to exploit will be able to control the data dictionary, including its addon and input key/values. This issue has been addressed in version 2023.9.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability. This issue is also tracked as GitHub Security Lab (GHSL) Vulnerability Report: `GHSL-2023-162`.
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Analysis
by VulDB Data Team • 11/11/2023
The vulnerability identified as CVE-2023-41899 affects Home Assistant, an open-source home automation platform that enables users to control and monitor their home environment through various connected devices. This particular flaw resides within the `hassio.addon_stdin` service which is part of the Supervisor component responsible for managing add-ons within the Home Assistant ecosystem. The vulnerability represents a partial Server-Side Request Forgery (SSRF) that allows authenticated attackers to exploit a path traversal mechanism within the Supervisor REST API endpoints. The flaw stems from insufficient input validation and sanitization when processing requests through the stdin service, creating a potential attack vector where malicious actors can manipulate the data dictionary structure to execute unauthorized API calls.
The technical implementation of this vulnerability allows an attacker who has already gained access to the hassio.addon_stdin service to invoke any Supervisor REST API endpoints through POST requests. This occurs because the system fails to properly validate or restrict the parameters passed to the stdin service, specifically the addon and input key/value combinations within the data dictionary. The attacker can control these parameters to redirect requests to internal Supervisor endpoints that should otherwise be restricted from external access. This represents a critical security gap as it bypasses normal access controls and authentication mechanisms that protect the Supervisor API from unauthorized manipulation. The vulnerability is categorized under CWE-918, which specifically addresses Server-Side Request Forgery vulnerabilities where applications fail to properly validate or sanitize user-supplied input that influences HTTP requests.
The operational impact of this vulnerability extends beyond simple unauthorized access to include complete control over the Supervisor's add-on management capabilities. An attacker who successfully exploits this vulnerability can potentially manipulate, install, or remove add-ons within the Home Assistant environment, which could lead to complete system compromise. The attack surface is particularly concerning because it allows for arbitrary code execution through the manipulation of add-on configurations and could enable attackers to establish persistent backdoors or exfiltrate sensitive data from the home automation system. This vulnerability affects all versions prior to 2023.9.0 and represents a significant risk to users who have not yet upgraded their systems. The issue is further compounded by the fact that the vulnerability is tracked under the GitHub Security Lab (GHSL) vulnerability report GHSL-2023-162, indicating that it has been recognized and documented by security researchers within the open-source community.
Mitigation strategies for CVE-2023-41899 center exclusively on upgrading to version 2023.9.0 or later, as no known workarounds exist for this particular vulnerability. Organizations and individuals utilizing Home Assistant systems must immediately implement the upgrade process to protect against potential exploitation. The vulnerability does not support any form of temporary patching or configuration changes that would prevent the exploitation, as the core issue lies within the fundamental design of how the stdin service processes user input parameters. This vulnerability aligns with ATT&CK technique T1059.007, which covers the use of scripting languages for execution, as attackers could leverage the compromised add-on management system to execute malicious code within the home automation environment. Security teams should also implement network segmentation and access controls to limit exposure to the Supervisor API endpoints, although the primary defense remains the mandatory software upgrade to address the root cause of the vulnerability.