CVE-2021-47002 is a vulnerability identified in the Linux kernel's SUNRPC subsystem, specifically related to the handling of Remote Procedure Calls (RPC). The flaw arises in the svc_rqst_alloc() and svc_rqst_free() functions, which manage request structures for RPC services. When the function alloc_pages_node() fails and returns a null pointer during the allocation of memory pages in svc_rqst_alloc(), the subsequent cleanup function svc_rqst_free() attempts to dereference this null pointer (rq_scratch_page) when calling put_page(). This results in a null pointer dereference, which can cause the kernel to crash or behave unpredictably, leading to a denial of service (DoS) condition. The vulnerability is rooted in insufficient null pointer checks before dereferencing pointers during memory management in the RPC service code. The fix involves adding a null check before calling put_page() to prevent dereferencing a null pointer. Although this vulnerability does not appear to have known exploits in the wild, its presence in the Linux kernel—a critical component of many systems—makes it a significant concern. The affected versions are specific Linux kernel commits identified by their hashes, indicating that this issue is relevant to certain kernel builds prior to the patch. Since the vulnerability is in the kernel, exploitation could impact any system running an affected Linux kernel version, especially those exposing RPC services. The lack of a CVSS score suggests it is a recently published issue, but the technical details and the nature of the flaw allow for a severity assessment based on impact and exploitability factors.

For European organizations, the impact of CVE-2021-47002 could be substantial, particularly for enterprises and service providers relying on Linux-based infrastructure that exposes RPC services. A successful exploitation leads to a kernel crash, causing denial of service, which can disrupt critical services, affect availability, and potentially lead to operational downtime. This is especially critical for sectors such as finance, healthcare, telecommunications, and government agencies where Linux servers are widely deployed. Although the vulnerability does not directly enable privilege escalation or remote code execution, the resulting DoS can be leveraged as part of a broader attack strategy to degrade service or cause outages. Additionally, the disruption of RPC services could impact distributed systems and applications that rely on RPC for inter-process communication. Given the widespread use of Linux in cloud environments, data centers, and embedded systems across Europe, the vulnerability poses a risk to the continuity and reliability of IT services.

To mitigate CVE-2021-47002, European organizations should prioritize updating their Linux kernels to versions that include the patch addressing this null pointer dereference. Since the vulnerability is in the kernel, applying vendor-supplied kernel updates or recompiling the kernel with the fix is essential. Organizations should: 1) Identify all systems running affected Linux kernel versions, especially those exposing SUNRPC services. 2) Apply the latest security patches from their Linux distribution vendors promptly. 3) Where immediate patching is not feasible, consider temporarily disabling or restricting access to RPC services using firewall rules or network segmentation to limit exposure. 4) Monitor system logs and kernel crash reports for signs of exploitation attempts or instability related to RPC services. 5) Implement robust incident response plans to quickly address potential DoS incidents. 6) Engage with Linux distribution security advisories and maintain an updated inventory of kernel versions in use to ensure timely patch management. These steps go beyond generic advice by focusing on kernel-level patching, service exposure reduction, and proactive monitoring specific to this vulnerability.