CVE-2024-21803 is a Use After Free (UAF) vulnerability identified in the Linux kernel, specifically affecting the Bluetooth modules within the kernel source file af_bluetooth.c. This vulnerability impacts Linux kernel versions starting from v2.6.12-rc2 up to but not including v6.8-rc1. The flaw arises when the kernel improperly manages memory, leading to a scenario where a previously freed memory region is accessed again. Such a condition can cause undefined behavior, including potential kernel crashes or, in some cases, local code execution. The vulnerability is local, meaning an attacker must have some level of access to the system to exploit it. The CVSS v3.1 base score is 3.5, indicating a low severity primarily due to the high attack complexity and the requirement for low privileges but no user interaction. The impact vector is network (AV:N), but the attack complexity is high (AC:H), and privileges required are low (PR:L). The vulnerability affects confidentiality and integrity minimally but can impact availability by causing denial of service through kernel crashes. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability is rooted in the Bluetooth subsystem, which is commonly enabled on many Linux systems, including servers, desktops, and embedded devices. Given the wide deployment of the Linux kernel across architectures such as x86 and ARM, this vulnerability has a broad potential impact surface. However, exploitation is constrained by the need for local access and the complexity of triggering the flaw reliably.

For European organizations, the impact of CVE-2024-21803 is primarily related to system stability and availability. Organizations relying on Linux systems with Bluetooth enabled—such as enterprise desktops, laptops, and IoT devices—could experience kernel crashes leading to denial of service conditions. While the vulnerability does not directly compromise confidentiality or integrity, disruption of critical systems could affect business operations, especially in sectors with high availability requirements like finance, healthcare, and telecommunications. The local nature of the exploit limits remote attacks, but insider threats or compromised user accounts could leverage this vulnerability to disrupt services. Additionally, embedded Linux devices used in industrial control systems or smart infrastructure across Europe might be affected if they run vulnerable kernel versions with Bluetooth enabled. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

European organizations should prioritize the following mitigations: 1) Identify and inventory all Linux systems running kernel versions from v2.6.12-rc2 up to v6.8-rc1, focusing on those with Bluetooth enabled. 2) Apply kernel updates or patches as soon as they become available from trusted Linux distributions or kernel maintainers. If official patches are not yet released, consider disabling Bluetooth modules on critical systems where feasible to reduce the attack surface. 3) Implement strict access controls to limit local user privileges, minimizing the risk of exploitation by low-privileged users. 4) Monitor system logs and kernel messages for unusual Bluetooth-related errors or crashes that could indicate attempted exploitation. 5) For embedded and IoT devices, coordinate with vendors to ensure timely firmware updates or mitigations. 6) Employ host-based intrusion detection systems (HIDS) that can detect anomalous kernel behavior or memory corruption attempts. 7) Educate system administrators and security teams about this vulnerability to ensure rapid response and patch management.