CVE-2024-43872 is a vulnerability identified in the Linux kernel related to the handling of Completion Event Queue Entries (CEQEs) in the RDMA (Remote Direct Memory Access) subsystem, specifically the hns (HiSilicon Network Subsystem) driver. The issue arises because CEQEs are currently processed within an interrupt handler context. Under conditions of heavy CEQE load, this design causes the CPU core to remain in interrupt context for an extended period, potentially leading to a soft lockup—a state where the CPU appears to be stuck and unable to process other tasks effectively. The vulnerability is addressed by moving the handling of CEQEs from the interrupt handler to a bottom half (BH) workqueue, which allows deferred processing outside the interrupt context. Additionally, an upper limit is imposed on the number of CEQEs processed in a single invocation of the work handler to prevent excessive CPU time consumption. This fix reduces the risk of CPU soft lockups under heavy network load conditions involving RDMA operations. While no known exploits are reported in the wild, the vulnerability could impact system stability and availability, especially in environments with high RDMA traffic. The affected versions are specific Linux kernel commits identified by the hash a5073d6054f75d7c94b3354206eec4b804d2fbd4. No CVSS score has been assigned yet, and no direct authentication or user interaction is required to trigger the issue, as it is related to kernel-level interrupt processing.

For European organizations, particularly those operating data centers, cloud infrastructure, or high-performance computing environments that utilize RDMA for low-latency, high-throughput networking, this vulnerability could lead to system instability and degraded service availability. Soft lockups in CPU cores can cause performance bottlenecks, delayed processing, or even kernel panics if unmitigated, potentially disrupting critical business operations. Industries such as telecommunications, financial services, research institutions, and large enterprises relying on Linux-based servers with RDMA-enabled network interfaces may experience increased risk. The impact is primarily on availability and system reliability rather than confidentiality or integrity. Given the widespread use of Linux in European IT infrastructure, especially in server and cloud environments, the vulnerability could affect a broad range of organizations if they run affected kernel versions without the patch. However, the absence of known exploits reduces the immediate threat level, though the potential for denial-of-service conditions under heavy load remains a concern.

European organizations should prioritize updating their Linux kernel to the patched versions that address CVE-2024-43872. Since the fix involves kernel-level changes, applying the latest stable kernel releases or vendor-provided security updates is essential. For environments where immediate patching is challenging, administrators should monitor RDMA traffic and system CPU usage closely to detect early signs of soft lockups or performance degradation. Limiting RDMA workload intensity or temporarily disabling RDMA features on affected systems can serve as a short-term mitigation. Additionally, organizations should review their kernel configuration and interrupt handling policies to ensure optimal processing of network events. Engaging with Linux distribution vendors for backported patches and security advisories is recommended. Implementing robust monitoring and alerting for kernel soft lockups and system responsiveness will help in early detection and response. Finally, testing patches in staging environments before production deployment will minimize operational risks.