CVE-2024-38620 addresses a vulnerability in the Linux kernel related to the Bluetooth Host Controller Interface (HCI) subsystem, specifically concerning the removal of HCI_AMP (Alternate MAC/PHY) support. The vulnerability stems from legacy support for AMP controllers, which have become obsolete due to the removal of BT_HS (Bluetooth High Speed) functionality. The Linux kernel previously differentiated between AMP and Primary controllers, managing them separately via the hdev->dev_type attribute. With the deprecation of AMP controllers, this differentiation is no longer necessary, and the kernel code has been updated to remove HCI_AMP support and the associated capability to create AMP controllers. This change simplifies the Bluetooth stack by retaining only HCI_PRIMARY controller support. The vulnerability itself is related to the presence of outdated code paths and capabilities that could potentially be exploited if AMP controllers were still active or accessible. However, the patch removes these legacy components, thereby eliminating the attack surface related to AMP controllers. No known exploits are reported in the wild, and the vulnerability does not have an assigned CVSS score. The update reflects a security hardening measure by removing unnecessary legacy code that could be leveraged for attacks, improving the overall security posture of the Linux Bluetooth subsystem.

For European organizations, the impact of CVE-2024-38620 is primarily relevant to those relying on Linux-based systems with Bluetooth functionality, especially in environments where Bluetooth connectivity is critical, such as manufacturing, healthcare, transportation, and IoT deployments. The removal of HCI_AMP support reduces the attack surface and potential for exploitation of legacy Bluetooth vulnerabilities. While no active exploits are known, failure to apply this patch could leave systems vulnerable to attacks targeting outdated Bluetooth controller implementations, potentially leading to unauthorized access, data interception, or denial of service. Given the widespread use of Linux in servers, embedded devices, and desktops across Europe, unpatched systems could be at risk of Bluetooth-related security issues. However, the direct impact is somewhat limited by the obsolescence of AMP controllers and the fact that modern Bluetooth devices predominantly use primary controllers. Organizations with legacy hardware or specialized Bluetooth configurations may face higher risk if they do not update. Overall, the vulnerability's resolution enhances Bluetooth security and stability, which is critical for maintaining secure wireless communications in European enterprises and public sector infrastructures.

European organizations should prioritize updating their Linux kernel versions to include the patch that removes HCI_AMP support. Specific mitigation steps include: 1) Audit all Linux systems to identify kernel versions and Bluetooth stack implementations to confirm if they are affected. 2) Deploy kernel updates from trusted Linux distributions that incorporate the fix for CVE-2024-38620. 3) For embedded or specialized devices, coordinate with vendors to ensure firmware or kernel updates are applied. 4) Disable or restrict Bluetooth functionality on systems where it is not required to reduce exposure. 5) Monitor Bluetooth-related logs and network activity for unusual behavior that could indicate exploitation attempts. 6) Implement network segmentation and access controls to limit Bluetooth device interactions within sensitive environments. 7) Maintain an inventory of Bluetooth-enabled devices and ensure they comply with updated security policies. These targeted actions go beyond generic advice by focusing on Bluetooth subsystem-specific updates and operational controls relevant to this vulnerability.