CVE-2023-27482 Overview
CVE-2023-27482 is a critical authentication bypass vulnerability affecting Home Assistant, an open source home automation platform. A remotely exploitable flaw was discovered that allows attackers to bypass authentication when accessing the Supervisor API through Home Assistant. This vulnerability impacts all Home Assistant installation types that use Supervisor version 2023.01.1 or older, potentially giving unauthorized users complete control over smart home environments.
Critical Impact
Remote attackers can bypass authentication to access the Supervisor API without valid credentials, potentially gaining full control over Home Assistant installations and connected IoT devices.
Affected Products
- Home Assistant Supervisor versions prior to 2023.03.1
- Home Assistant Core versions prior to 2023.3.0
- All Home Assistant installation types using vulnerable Supervisor (excluding Container and Core-only installations)
Discovery Timeline
- 2023-03-08 - CVE-2023-27482 published to NVD
- 2023-03-08 - Home Assistant releases security patch (Supervisor 2023.03.1)
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-27482
Vulnerability Analysis
This authentication bypass vulnerability (CWE-287) allows remote attackers to access the Supervisor API without proper authentication. The Supervisor component acts as the management layer for Home Assistant installations, controlling system updates, add-ons, snapshots, and core system functions. By bypassing authentication, attackers gain unauthorized access to these critical management functions.
The vulnerability is particularly severe because the Supervisor API provides extensive control over the Home Assistant environment, including the ability to install arbitrary add-ons, access configuration files, and potentially execute commands on the underlying system. Installations exposed directly to the internet without additional authentication layers are at the highest risk.
Root Cause
The vulnerability stems from improper authentication validation (CWE-287) in the Supervisor API endpoints. The authentication mechanism failed to properly validate incoming requests under certain conditions, allowing attackers to craft requests that bypass the intended security controls and gain unauthorized access to protected API functions.
Attack Vector
The attack is network-based and requires no user interaction or prior authentication. An attacker with network access to a vulnerable Home Assistant instance can send specially crafted requests to the Supervisor API endpoints. The attack complexity is low, making exploitation straightforward for attackers who can reach the target system.
The vulnerability is especially dangerous for installations exposed to the internet without VPN protection or reverse proxy authentication. Attackers can enumerate potential targets by scanning for Home Assistant instances and then exploit the authentication bypass to gain full control.
For detailed technical analysis of the exploitation mechanism, refer to the Elttam PwnAssistant writeup and the security advisory publication.
Detection Methods for CVE-2023-27482
Indicators of Compromise
- Unexpected API requests to Supervisor endpoints from external IP addresses
- Unauthorized add-on installations or configuration changes
- Anomalous authentication attempts in Home Assistant logs
- Unexpected snapshot creation or restoration activities
- Unusual network traffic patterns to Supervisor API ports
Detection Strategies
- Monitor Home Assistant Supervisor logs for authentication failures followed by successful API access
- Implement network monitoring to detect requests to Supervisor API endpoints from unauthorized sources
- Review Home Assistant configuration history for unexpected changes
- Audit installed add-ons and compare against approved baseline configurations
Monitoring Recommendations
- Enable detailed logging in Home Assistant Supervisor component
- Configure alerts for any external access to Supervisor API endpoints
- Implement intrusion detection rules for Home Assistant API traffic patterns
- Monitor for version changes indicating potential unauthorized updates
How to Mitigate CVE-2023-27482
Immediate Actions Required
- Update Home Assistant Supervisor to version 2023.03.1 or later immediately
- Upgrade Home Assistant Core to version 2023.3.0 or later
- Do not expose Home Assistant instances directly to the internet until patched
- Implement VPN or reverse proxy with additional authentication for remote access
Patch Information
Home Assistant has released patches addressing this vulnerability. Supervisor version 2023.03.1 contains the fix and has been automatically rolled out to affected installations via the auto-update feature. Home Assistant Core version 2023.3.0 also includes mitigation for this vulnerability. Users should verify their installations have been updated by checking the version numbers in the Home Assistant interface.
For official patch details, see the Home Assistant Security Disclosure and the GitHub Security Advisory GHSA-2j8f-h4mr-qr25.
Workarounds
- If unable to update immediately, block external access to Home Assistant at the firewall level
- Implement a VPN solution for remote access instead of exposing Home Assistant directly
- Use a reverse proxy with strong authentication (such as Authelia or Authentik) in front of Home Assistant
- Segment the Home Assistant network from untrusted networks using VLAN isolation
# Example: Block external access to Home Assistant using iptables
# Replace 192.168.1.0/24 with your trusted local network
iptables -A INPUT -p tcp --dport 8123 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 8123 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
