CVE-2024-42133 is a vulnerability identified in the Linux kernel's Bluetooth subsystem, specifically related to the handling of Bluetooth BIG (Broadcast Isochronous Group) synchronization events. The vulnerability arises from improper validation of handle values in the function hci_le_big_sync_established_evt. In this context, the handle is an identifier used internally by the kernel to manage Bluetooth connections and resources. The issue occurs because the kernel fails to correctly filter out handle values that are too large and belong to the IDA (ID allocator) ID range. Without this filtering, the kernel erroneously releases IDA resources during the cleanup process in hci_conn_cleanup, which can lead to resource mismanagement. This flaw could potentially cause memory corruption or use-after-free conditions within the Bluetooth stack, leading to instability or crashes of the kernel Bluetooth subsystem. Although no known exploits are reported in the wild as of the publication date, the vulnerability represents a risk vector for attackers who can send crafted Bluetooth packets to vulnerable Linux systems. The affected Linux kernel versions include several commits identified by their hashes, indicating that the issue is present in recent kernel builds prior to the patch. The vulnerability was reserved and published in late July 2024, and no CVSS score has been assigned yet. The fix involves adding proper validation to ignore handle values that exceed expected ranges, preventing erroneous resource release and improving the robustness of the Bluetooth stack.

For European organizations, the impact of CVE-2024-42133 could be significant in environments where Linux systems with Bluetooth capabilities are widely deployed. This includes corporate laptops, IoT devices, embedded systems, and industrial control systems that rely on Linux kernels with Bluetooth support. Exploitation could lead to denial of service through kernel crashes or potentially enable privilege escalation if memory corruption is leveraged by an attacker. This is particularly concerning for sectors such as manufacturing, healthcare, and critical infrastructure, where Bluetooth-enabled devices are common and system availability and integrity are paramount. Additionally, organizations with remote or mobile workforces using Linux laptops with Bluetooth peripherals could face increased risk if attackers exploit this vulnerability to disrupt operations or gain unauthorized access. The absence of known exploits reduces immediate risk, but the vulnerability's presence in the kernel Bluetooth stack means that attackers with physical proximity or network access to Bluetooth interfaces could attempt exploitation. Given the widespread use of Linux in European enterprise and government environments, unpatched systems could be vulnerable to targeted attacks or opportunistic scanning.

To mitigate CVE-2024-42133, European organizations should prioritize updating their Linux kernel versions to the latest patched releases that include the fix for this vulnerability. Kernel updates should be tested and deployed promptly, especially on systems with active Bluetooth interfaces. Organizations should audit their Linux device inventories to identify systems with Bluetooth enabled and assess exposure. Where possible, disable Bluetooth functionality on devices that do not require it to reduce the attack surface. For critical systems where immediate patching is not feasible, consider implementing network segmentation and access controls to limit Bluetooth exposure. Monitoring Bluetooth-related kernel logs for unusual activity or crashes can help detect exploitation attempts. Additionally, organizations should ensure that endpoint security solutions are configured to detect anomalous behavior related to Bluetooth stack exploitation. For embedded or IoT devices running Linux, coordinate with vendors to obtain patched firmware or kernel updates. Finally, maintain awareness of any emerging exploit reports or security advisories related to this vulnerability to adapt defenses accordingly.