CVE-2024-56653 is a high-severity use-after-free (UAF) vulnerability in the Linux kernel's Bluetooth subsystem, specifically within the MediaTek Bluetooth driver component (btmtk). The flaw arises in the function btmtk_process_coredump, where improper handling of socket buffers (skbs) leads to a use-after-free condition. The vulnerability is triggered when the function hci_devcd_append releases an skb, but subsequent code attempts to access this freed memory, causing a read of invalid memory. This is confirmed by Kernel Address Sanitizer (KASAN) reports indicating slab-use-after-free errors. The root cause is a logic error in managing the lifecycle of Bluetooth core dump data structures, where the increment of a counter (data->cd_info.cnt) occurs only after a successful call to hci_devcd_append, but the check for completion uses a strict greater-than comparison instead of greater-than-or-equal, leading to premature access of freed memory. Exploitation requires local privileges (low complexity) without user interaction, and the impact includes full compromise of confidentiality, integrity, and availability of the affected system due to kernel-level memory corruption. The vulnerability affects Linux kernel versions including 6.6.40 and likely others incorporating the vulnerable btmtk driver code. No known exploits are currently reported in the wild, but the nature of the flaw and its kernel-level impact make it a critical target for attackers seeking privilege escalation or denial of service.

For European organizations, this vulnerability poses a significant risk, especially for those relying on Linux-based systems with Bluetooth functionality enabled, such as enterprise servers, workstations, and embedded devices. Successful exploitation could allow attackers to execute arbitrary code with kernel privileges, leading to complete system compromise, data theft, or disruption of critical services. Industries with high Bluetooth usage, including telecommunications, manufacturing (IoT devices), healthcare (medical devices), and public sector infrastructure, are particularly vulnerable. The vulnerability could also facilitate lateral movement within networks if exploited on endpoint devices. Given the widespread deployment of Linux in European data centers and critical infrastructure, the impact could extend to national security, privacy compliance (GDPR), and operational continuity. The requirement for local privileges somewhat limits remote exploitation but does not eliminate risk, as attackers could leverage other vulnerabilities or social engineering to gain initial access.

European organizations should prioritize patching Linux kernels to versions that include the fix for CVE-2024-56653 as soon as updates are available from their Linux distribution vendors. Until patches are applied, organizations should: 1) Disable or restrict Bluetooth functionality on systems where it is not essential, especially on critical servers and endpoints. 2) Implement strict access controls and monitoring to prevent unauthorized local access, including hardened user privilege management and use of endpoint detection and response (EDR) tools to detect suspicious kernel activity. 3) Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and enable Kernel Page Table Isolation (KPTI) to reduce exploitation likelihood. 4) Conduct thorough audits of devices with MediaTek Bluetooth chipsets to identify vulnerable systems. 5) Educate users on the risks of local privilege escalation and enforce policies to limit installation of untrusted software that could be used to exploit this vulnerability. 6) Monitor security advisories and threat intelligence feeds for any emerging exploit attempts targeting this CVE.