CVE-2025-67399 Overview
A sensitive information disclosure vulnerability exists in the AIRTH SMART HOME AQI MONITOR Bootloader version 1.005. The vulnerability allows a physically proximate attacker to obtain sensitive information by accessing the unprotected UART port on the BK7231N controller, which handles both Wi-Fi and BLE module communications. This hardware-level vulnerability exposes confidential device data to unauthorized parties with physical access to the device.
Critical Impact
Attackers with physical access can extract sensitive device configuration, credentials, and potentially compromise the entire smart home network through the exposed UART debug interface.
Affected Products
- AIRTH SMART HOME AQI MONITOR with Bootloader version 1.005
- Devices utilizing the BK7231N Wi-Fi and BLE controller module
- Smart home air quality monitoring systems from AIRTH
Discovery Timeline
- January 14, 2026 - CVE-2025-67399 published to NVD
- January 14, 2026 - Last updated in NVD database
Technical Details for CVE-2025-67399
Vulnerability Analysis
This vulnerability falls under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). The core issue stems from the UART (Universal Asynchronous Receiver-Transmitter) port on the BK7231N controller being left open and accessible without any authentication or access controls.
The BK7231N is a popular IoT chip used in smart home devices that provides both Wi-Fi and Bluetooth Low Energy (BLE) connectivity. When the UART interface is left unsecured, it creates a direct communication channel to the device's bootloader and potentially the running firmware. This allows attackers to read sensitive data including Wi-Fi credentials, device configuration, firmware contents, and potentially extract cryptographic keys stored on the device.
The physical access requirement means that exploitation requires the attacker to be in proximity to the device and have the ability to connect to the UART pins, typically through a USB-to-UART adapter. While this limits remote exploitation, it represents a significant security gap for devices deployed in shared spaces, rental properties, or areas accessible to malicious actors.
Root Cause
The root cause of this vulnerability is improper hardware security design in the bootloader implementation. The UART debug interface, which is commonly used during development and manufacturing, was not properly disabled or protected before the device was shipped to consumers. This is a common oversight in IoT device manufacturing where debug interfaces are left enabled for potential field debugging or firmware updates but are not secured against unauthorized access.
The BK7231N controller's bootloader at version 1.005 does not implement any authentication mechanism or access controls for the UART port, allowing anyone with physical access to interact with the bootloader directly.
Attack Vector
The attack requires physical proximity to the target device. An attacker would need to:
- Gain physical access to the AIRTH SMART HOME AQI MONITOR device
- Open the device enclosure to access the internal circuit board
- Identify and connect to the UART pins on the BK7231N controller
- Use a USB-to-UART adapter connected to a computer to establish communication
- Interact with the bootloader to extract sensitive information
The exploitation does not require any privileges or user interaction, making it straightforward for anyone with basic hardware hacking knowledge. The attack specifically targets the confidentiality of the device's stored information without affecting integrity or availability.
Detection Methods for CVE-2025-67399
Indicators of Compromise
- Physical evidence of device tampering or enclosure being opened
- Unauthorized solder points or wires connected to the internal circuit board
- Signs of UART pin headers being accessed or modified
- Unusual network behavior from the device indicating credential compromise
Detection Strategies
- Implement physical tamper detection mechanisms on deployed devices
- Monitor for new device registrations on the network using credentials from compromised units
- Track MAC addresses of AQI monitors and alert on duplicate or cloned devices appearing on the network
- Review access logs for unusual authentication patterns from smart home devices
Monitoring Recommendations
- Enable logging on smart home hubs to detect abnormal device behavior
- Monitor Wi-Fi network for unauthorized devices that may be using stolen credentials
- Implement network segmentation to isolate IoT devices and limit exposure if credentials are compromised
- Conduct periodic physical audits of deployed smart home devices in accessible locations
How to Mitigate CVE-2025-67399
Immediate Actions Required
- Deploy affected devices in physically secure locations with limited public access
- Consider adding tamper-evident seals to device enclosures to detect unauthorized access
- Change Wi-Fi network credentials if device tampering is suspected
- Implement network segmentation to limit the impact of credential disclosure
- Contact AIRTH support for guidance on securing deployed devices
Patch Information
No official firmware patch has been announced at the time of publication. Users should monitor the Airth Company Website for security updates and firmware releases. Additional technical details about this vulnerability are available in the GitHub CVE-2025-67399 Document.
Workarounds
- Physically secure all deployed AIRTH SMART HOME AQI MONITOR devices
- Apply epoxy or conformal coating over UART pins to prevent easy access (note: this may void warranty)
- Deploy devices only in trusted, access-controlled environments
- Implement strong network security measures including WPA3 encryption and network monitoring
- Consider replacing vulnerable devices with models that have secured debug interfaces
# Network segmentation example for IoT devices
# Create a separate VLAN for IoT devices to limit exposure
# Example using standard VLAN configuration
# 1. Create IoT VLAN (example VLAN ID 100)
# 2. Assign IoT devices including AQI monitor to this VLAN
# 3. Configure firewall rules to restrict IoT VLAN access
# Monitor for suspicious connections from IoT VLAN
# Review logs for any unauthorized access attempts
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
