CVE-2024-26886 is a medium-severity vulnerability identified in the Linux kernel's Bluetooth subsystem, specifically within the af_bluetooth module. The issue arises from a deadlock condition triggered by improper locking mechanisms during socket operations, particularly when invoking sock_lock on the .recvmsg function. This deadlock occurs because the code attempts to lock the socket using sock_sock, which can lead to a use-after-free (UAF) scenario. The fix involves replacing the problematic sock_sock lock with the sk_receive_queue.lock on the bt_sock_ioctl function to prevent the deadlock and associated UAF. The vulnerability manifests as a task (kworker thread) being blocked for an extended period (over 30 seconds), indicating a severe hang or stall in kernel processing related to Bluetooth socket communication. The vulnerability is tracked under CWE-416 (Use After Free), which can cause system instability or denial of service (DoS) conditions. The CVSS v3.1 score is 6.5, reflecting a medium severity with an attack vector of adjacent network (AV:A), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), but high impact on availability (A:H). No known exploits are reported in the wild as of the publication date (April 17, 2024). The affected versions are various Linux kernel commits prior to the fix, indicating that multiple kernel versions could be vulnerable if they include the affected Bluetooth stack code. The vulnerability primarily affects systems using Linux kernels with Bluetooth enabled and handling socket communications via the af_bluetooth module.

For European organizations, the primary impact of CVE-2024-26886 is the potential for denial of service (DoS) on Linux-based systems that utilize Bluetooth functionality. This can cause critical system processes to hang or become unresponsive, particularly in environments where Bluetooth communication is integral, such as in IoT deployments, industrial control systems, or enterprise devices with Bluetooth peripherals. The deadlock can degrade system availability, potentially disrupting business operations, especially in sectors relying on real-time data or continuous connectivity. Although the vulnerability does not compromise confidentiality or integrity, the availability impact can lead to operational downtime, increased maintenance costs, and potential safety risks in critical infrastructure. Given the widespread use of Linux in servers, embedded devices, and workstations across Europe, organizations with Bluetooth-enabled Linux systems are at risk. The lack of required privileges or user interaction for exploitation means that an attacker with adjacent network access (e.g., Bluetooth range) could trigger the deadlock remotely, increasing the threat surface in environments with physical proximity to attackers. However, the absence of known exploits in the wild reduces immediate risk but does not eliminate the need for prompt mitigation.

European organizations should implement the following specific mitigation strategies: 1) Apply the latest Linux kernel updates that include the patch for CVE-2024-26886 as soon as they become available from trusted Linux distributions or kernel maintainers. 2) For systems where immediate patching is not feasible, consider disabling Bluetooth functionality if it is not essential, thereby eliminating the attack vector. 3) Monitor kernel logs and system performance metrics for signs of task blocking or deadlocks related to Bluetooth socket operations to detect potential exploitation attempts early. 4) Restrict physical and network access to Bluetooth interfaces, employing Bluetooth device management policies to limit pairing and communication to trusted devices only. 5) Employ network segmentation and access controls to minimize exposure of Bluetooth-enabled Linux systems to untrusted or adjacent networks. 6) For critical infrastructure or industrial environments, conduct thorough testing of kernel updates in controlled environments to ensure stability before deployment. 7) Maintain an inventory of Linux systems with Bluetooth enabled to prioritize patching and mitigation efforts effectively.