CVE-2025-5476 in XAV-AX8500
Summary
by MITRE • 06/21/2025
Sony XAV-AX8500 Bluetooth Improper Isolation Authentication Bypass Vulnerability. This vulnerability allows network-adjacent attackers to bypass authentication on affected Sony XAV-AX8500 devices. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the implementation of ACL-U links. The issue results from the lack of L2CAP channel isolation. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-26284.
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Analysis
by VulDB Data Team • 07/08/2025
The CVE-2025-5476 vulnerability represents a critical authentication bypass flaw in Sony XAV-AX8500 automotive infotainment systems that operates at the Bluetooth protocol layer. This vulnerability specifically targets the ACL-U (Active Connection Link - Unicast) implementation within the Bluetooth stack, creating a fundamental security weakness that allows attackers to gain unauthorized access to the device's functionality without proper authentication credentials. The flaw exists in the wireless communication protocols used by automotive entertainment systems, making it particularly concerning for vehicle security and connected car environments. The vulnerability affects Sony XAV-AX8500 devices that utilize Bluetooth connectivity for various vehicle functions including audio streaming, phone integration, and infotainment services. This authentication bypass capability means that any attacker within network-adjacent range can exploit the system without needing legitimate credentials or access tokens, creating a significant risk for automotive cybersecurity.
The technical root cause of this vulnerability stems from inadequate Layer 2 Communication Access Control Protocol (L2CAP) channel isolation mechanisms within the Bluetooth implementation of the Sony XAV-AX8500. Specifically, the system fails to properly enforce channel separation between different Bluetooth communication paths, allowing malicious actors to manipulate or intercept data streams across multiple L2CAP channels simultaneously. This lack of proper channel isolation creates a pathway for attackers to bypass the authentication mechanisms that should normally protect access to the device's Bluetooth services. The vulnerability manifests when an attacker leverages the improperly isolated L2CAP channels to establish unauthorized communication sessions, effectively circumventing the normal authentication flow that would typically require valid credentials. This architectural flaw falls under the CWE-307 weakness category, which specifically addresses improper restriction of excessive authentication attempts or the failure to properly implement authentication controls. The vulnerability is particularly dangerous because it operates at the network layer where attackers can exploit the Bluetooth stack without requiring physical access to the vehicle or specialized equipment beyond standard wireless attack tools.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential vehicle control system compromise and data privacy breaches. An attacker exploiting this vulnerability could potentially gain access to vehicle audio systems, phone connectivity features, and other Bluetooth-enabled services that may contain sensitive information or provide pathways to deeper vehicle systems. The vulnerability's network-adjacent nature means that attackers do not require sophisticated equipment or physical proximity to the vehicle to exploit the flaw, as the Bluetooth signals can be intercepted from a reasonable distance. This creates a significant risk for automotive environments where vehicle security is paramount, as the vulnerability could enable attackers to access personal data stored on connected devices, intercept communication streams, or potentially gain access to other vehicle systems that may be connected through the same Bluetooth infrastructure. The lack of authentication requirements for exploitation makes this vulnerability particularly concerning for automotive cybersecurity frameworks and vehicle safety standards.
Mitigation strategies for this vulnerability should focus on immediate firmware updates from Sony, which would address the L2CAP channel isolation implementation and restore proper authentication mechanisms. Network administrators and vehicle security teams should implement Bluetooth access controls and disable unnecessary Bluetooth services when not actively required. The vulnerability requires a fundamental reimplementation of the ACL-U link handling within the Bluetooth stack to properly isolate L2CAP channels and enforce authentication requirements. Organizations should also consider implementing network monitoring solutions that can detect anomalous Bluetooth traffic patterns that may indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1566 which covers credential harvesting through social engineering and network attacks, though in this case the attack vector is more direct through protocol manipulation rather than social engineering. The remediation process should involve comprehensive testing of the updated Bluetooth stack to ensure that proper channel isolation is maintained and that authentication mechanisms function correctly under various network conditions. Additionally, vehicle manufacturers should consider implementing robust Bluetooth security frameworks that align with automotive cybersecurity standards such as ISO/SAE 21434 and NIST SP 800-160 to prevent similar issues in future vehicle systems.