CVE-2023-52766 is a vulnerability identified in the Linux kernel specifically within the i3c subsystem, more precisely in the mipi-i3c-hci driver component. The flaw arises in the hci_dma_irq_handler() function, which handles DMA (Direct Memory Access) interrupts for the I3C Host Controller Interface. The vulnerability is due to an out-of-bounds memory access caused by the function looping over ring headers that have not been allocated or enabled during initialization (hci_dma_init()). When the handler accesses rings->headers[i] with an index i that exceeds the number of allocated ring headers, it results in an out-of-bounds read or write. This can lead to undefined behavior including potential kernel crashes (denial of service) or memory corruption, which could be leveraged by an attacker to escalate privileges or execute arbitrary code within the kernel context. The issue was fixed by ensuring the handler only processes ring headers that were properly allocated and enabled, preventing invalid memory accesses. The vulnerability affects Linux kernel versions identified by the commit hash 3a379bbcea0af6280e1ca0d1edfcf4e68cde6ee0 and similar builds. No known exploits are reported in the wild as of the publication date (May 21, 2024). No CVSS score has been assigned yet, and no public patches or exploit code have been linked. The vulnerability is technical and low-level, requiring kernel-level access or the ability to trigger the DMA interrupt handler with crafted inputs, which may limit exploitation scenarios to privileged or local attackers or specific hardware configurations utilizing the I3C interface.

For European organizations, the impact of CVE-2023-52766 depends largely on the deployment of Linux systems running vulnerable kernel versions with the i3c subsystem enabled and in use. The I3C interface is typically found in embedded systems, IoT devices, and certain specialized hardware platforms. Organizations relying on Linux-based infrastructure in sectors such as telecommunications, industrial control systems, or embedded device manufacturing may be at higher risk. Exploitation could lead to kernel crashes causing denial of service, potentially disrupting critical services or operations. More severe impacts could include privilege escalation or arbitrary code execution within the kernel, compromising system integrity and confidentiality. This is particularly concerning for environments requiring high security and uptime, such as financial institutions, healthcare providers, and critical infrastructure operators in Europe. However, the absence of known exploits and the technical complexity of triggering this vulnerability reduce the immediate risk. Nonetheless, unpatched systems remain vulnerable to future exploit development, especially as attackers often target Linux kernels due to their widespread use in servers and embedded devices.

European organizations should prioritize updating their Linux kernel to versions that include the fix for CVE-2023-52766. This involves applying the latest stable kernel updates from trusted Linux distributions or compiling kernels with the patched code. For embedded or IoT devices, vendors should be contacted to obtain firmware updates incorporating the fix. Organizations should audit their environments to identify systems using the i3c subsystem and assess whether the hardware and kernel versions are vulnerable. Where immediate patching is not feasible, mitigating controls include restricting access to systems with the vulnerable kernel, especially limiting local user privileges and preventing untrusted code execution that could trigger the DMA interrupt handler. Monitoring kernel logs for unusual DMA interrupt activity or crashes related to the i3c driver may help detect exploitation attempts. Additionally, implementing kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and Control Flow Integrity (CFI) can reduce exploitation success. Finally, organizations should maintain robust incident response plans to quickly address any exploitation attempts.