CVE-2025-5820 is a medium-severity vulnerability affecting the Sony XAV-AX8500, a multimedia receiver commonly used in automotive environments. The flaw resides in the Bluetooth ERTM (Enhanced Retransmission Mode) channel communication implementation, specifically due to improper initialization of channel data. This defect enables network-adjacent attackers to bypass authentication mechanisms without requiring any prior authentication or user interaction. By exploiting this vulnerability, an attacker can establish unauthorized access to the device's Bluetooth communication channel, potentially allowing them to interfere with or manipulate data exchanges. The vulnerability is classified under CWE-288, which pertains to authentication bypass through alternate paths or channels. The CVSS v3.0 base score is 6.3, reflecting a medium severity level, with attack vector as adjacent network, low attack complexity, no privileges required, and no user interaction needed. Although no known exploits are currently reported in the wild, the vulnerability poses a risk due to the critical role of Bluetooth connectivity in vehicle infotainment systems, which may interface with other vehicle systems or user devices. The affected version is 2.00.01 of the Sony XAV-AX8500. No patches have been publicly released at the time of this report.

For European organizations, particularly those in the automotive, transportation, and fleet management sectors, this vulnerability could have significant operational and security implications. Exploitation could allow attackers to bypass Bluetooth authentication, potentially leading to unauthorized access to vehicle infotainment systems. This access might be leveraged to intercept or manipulate communications, inject malicious commands, or pivot to other connected vehicle systems if network segmentation is insufficient. Confidentiality could be compromised by unauthorized data access, integrity could be affected by manipulation of data or commands, and availability might be impacted if the attacker disrupts Bluetooth communications. Given the increasing integration of infotainment systems with critical vehicle functions and personal devices, exploitation could also lead to privacy breaches or facilitate further attacks on corporate networks via connected devices. Although the attack vector is adjacent network, meaning the attacker must be within Bluetooth range (typically up to 100 meters), this is feasible in public or semi-public environments such as parking lots, service centers, or transport hubs. The lack of required authentication and user interaction lowers the barrier for exploitation, increasing the risk profile for organizations relying on these devices.

1. Immediate mitigation should focus on restricting physical and wireless access to vehicles equipped with the Sony XAV-AX8500, especially in sensitive or high-risk environments. 2. Organizations should monitor Bluetooth traffic for anomalous connection attempts or unusual activity related to the affected devices. 3. Implement strict network segmentation between vehicle infotainment systems and critical vehicle control or corporate IT networks to limit lateral movement in case of compromise. 4. Engage with Sony or authorized vendors to obtain firmware updates or patches as soon as they become available; proactively inquire about patch timelines given the absence of current patches. 5. Educate drivers and fleet operators about the risks of unauthorized Bluetooth connections and encourage disabling Bluetooth when not in use. 6. Consider deploying intrusion detection systems capable of monitoring Bluetooth protocol anomalies. 7. For organizations managing large fleets, conduct audits to identify vehicles with the affected device and prioritize risk assessments accordingly. 8. Evaluate alternative infotainment solutions or additional security controls if patching is delayed or unavailable.