CVE-2024-42132 is a vulnerability identified in the Linux kernel's Bluetooth subsystem, specifically within the Host Controller Interface (HCI) layer. The issue arises from improper handling of connection handles in the function hci_le_big_sync_established_evt(). The vulnerability occurs when a handle value larger than the defined maximum (HCI_CONN_HANDLE_MAX) is passed, causing the kernel to misinterpret the connection state. This leads to a warning triggered by Syzbot in the hci_conn_del() function, which attempts to free a handle that was never allocated via the expected ID allocator. The root cause is the absence of an upper bound check on the handle value in hci_le_big_sync_established_evt(), unlike the existing check in hci_conn_set_handle(). This flaw can cause inconsistent internal state management of Bluetooth connections, potentially leading to kernel warnings or instability. The Linux kernel maintainers have addressed this by adding the necessary upper bound validation to prevent invalid handle values from being processed. No known exploits are currently reported in the wild, and the vulnerability affects specific Linux kernel versions identified by their commit hashes. The issue is technical and low-level, impacting the Bluetooth HCI connection management code, which is critical for Bluetooth communications on Linux systems.

For European organizations, the impact of CVE-2024-42132 is primarily related to the stability and reliability of Bluetooth functionality on Linux-based systems. Many enterprises and public sector entities in Europe rely on Linux servers, desktops, and embedded devices that use Bluetooth for device connectivity, including IoT devices, industrial control systems, and user endpoints. While this vulnerability does not directly lead to remote code execution or privilege escalation, improper handle management could cause kernel warnings or crashes, potentially disrupting Bluetooth-dependent services or devices. This could affect operational continuity in environments where Bluetooth is integral, such as manufacturing, healthcare, or transportation sectors. Additionally, any instability in kernel Bluetooth handling might be leveraged in complex attack chains or denial-of-service scenarios, although no such exploits are currently known. The impact on confidentiality and integrity is minimal, but availability could be affected if the kernel instability leads to system crashes or degraded Bluetooth service. Organizations with extensive Linux deployments and Bluetooth usage should be aware of this vulnerability to maintain system reliability.

To mitigate CVE-2024-42132, European organizations should promptly apply the Linux kernel patches that address this vulnerability once they are available from their Linux distribution vendors or kernel maintainers. Since the vulnerability is in the kernel Bluetooth subsystem, updating to a patched kernel version is the most effective mitigation. Organizations should: 1) Identify all Linux systems using Bluetooth functionality, including servers, desktops, and embedded devices. 2) Monitor vendor advisories and apply kernel updates that include the fix for this CVE. 3) For critical systems where immediate patching is not feasible, consider disabling Bluetooth functionality temporarily to eliminate exposure. 4) Implement robust monitoring for kernel warnings or unusual Bluetooth-related logs that could indicate attempts to trigger this vulnerability. 5) Engage with device and software vendors to ensure embedded Linux devices receive timely updates. 6) Incorporate this vulnerability into vulnerability management and patching workflows to ensure ongoing compliance. These steps go beyond generic advice by focusing on Bluetooth-specific mitigation and operational monitoring tailored to the vulnerability's nature.