CVE-2021-47184 is a vulnerability identified in the Linux kernel's i40e network driver, which handles Intel Ethernet devices. The flaw arises from a NULL pointer dereference during the synchronization of VSI (Virtual Station Interface) filters. Specifically, the vulnerability occurs when the VSI filter list is updated after the VSI has already been removed. Without proper synchronization, the kernel attempts to access resources that have been freed, leading to a NULL pointer dereference and causing a kernel oops (crash). The patch introduces a new flag, I40E_VSI_RELEASING, to signal when VSI resources are being deleted and released, ensuring synchronization between the thread updating filters and the subtask managing filter synchronization. This prevents the update of VSI filters after the VSI has been removed, thereby eliminating the NULL pointer dereference and associated kernel crash. The vulnerability affects certain versions of the Linux kernel incorporating the i40e driver, which is used for Intel Ethernet devices. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability primarily threatens the stability and availability of systems running Linux kernels with the affected i40e driver, particularly those using Intel Ethernet hardware. A successful exploitation would cause a kernel crash, resulting in a denial of service (DoS) condition. This could disrupt critical network services, especially in data centers, cloud infrastructure, and enterprise environments relying on Linux servers for networking. While the vulnerability does not appear to allow privilege escalation or remote code execution, the resulting system crashes could lead to operational downtime, impacting business continuity and service availability. Organizations with high network traffic and reliance on Intel Ethernet devices are at increased risk of experiencing service interruptions. Given the absence of known exploits, the immediate threat level is moderate, but unpatched systems remain vulnerable to potential future exploitation or accidental crashes triggered by legitimate operations.

To mitigate this vulnerability, European organizations should promptly apply the official Linux kernel patches that address CVE-2021-47184, ensuring the i40e driver includes the I40E_VSI_RELEASING flag and synchronization fixes. System administrators should verify that their Linux distributions have incorporated these patches, particularly for kernels used in production environments with Intel Ethernet hardware. Additionally, organizations should implement robust monitoring of kernel logs to detect any kernel oops or crashes related to the i40e driver, enabling rapid response to potential exploitation attempts or instability. Network segmentation and redundancy can help minimize the impact of any service disruption caused by this vulnerability. For environments where immediate patching is not feasible, temporarily disabling or limiting the use of affected network interfaces may reduce exposure. Finally, maintaining up-to-date backups and disaster recovery plans will help ensure business continuity in case of unexpected system failures.