CVE-2021-47424 is a vulnerability in the Linux kernel specifically affecting the i40e network driver, which is used for Intel Ethernet devices. The issue arises during the initialization and setup of the Virtual Station Interface (VSI) in the i40e_probe() function, part of the Physical Function (PF) switch setup process. When VSI setup fails, the driver attempts to free miscellaneous IRQ (Interrupt Request) vectors that were never properly allocated. This results in a kernel Oops, a critical error that causes the kernel to crash or become unstable. The root cause is that the driver calls i40e_clear_interrupt_scheme(), which in turn calls free_irq() on IRQ vectors that are already freed or never allocated, leading to a double-free or invalid free operation. The patch for this vulnerability adds a check for the PF state flag __I40E_MISC_IRQ_REQUESTED before attempting to free the IRQ vectors, ensuring that the driver only frees IRQs that were successfully allocated. This vulnerability can cause system instability or denial of service (DoS) due to kernel crashes when the affected driver encounters certain error conditions during device initialization or reconfiguration. Since this is a kernel-level issue affecting a network driver, it impacts systems running Linux kernels with the vulnerable i40e driver version, particularly those using Intel Ethernet hardware supported by this driver. There is no indication of known exploits in the wild, and no CVSS score has been assigned yet. The vulnerability requires no user interaction but does require the presence of the affected hardware and driver, and it can be triggered during device initialization or reconfiguration failures.

For European organizations, the impact of CVE-2021-47424 can be significant in environments relying on Intel Ethernet devices supported by the i40e driver, especially in data centers, cloud infrastructure, and enterprise networks running Linux-based systems. The vulnerability can lead to kernel crashes and system instability, resulting in denial of service conditions that disrupt network connectivity and critical services. This can affect availability of networked applications, virtualized environments, and storage systems that depend on stable network interfaces. Organizations with high network throughput demands or those using advanced network virtualization features may experience increased risk. Additionally, repeated kernel crashes could lead to data loss or corruption in sensitive environments. Although no known exploits exist, the vulnerability's presence in the kernel means that attackers with local access or the ability to trigger device reinitialization could potentially cause service disruptions. This is particularly relevant for managed service providers, telecom operators, and enterprises with large Linux server deployments across Europe.

To mitigate CVE-2021-47424, European organizations should prioritize updating their Linux kernel to the latest patched version that includes the fix for this vulnerability. Specifically, ensure that the i40e driver version in use contains the check for __I40E_MISC_IRQ_REQUESTED before freeing IRQ vectors. System administrators should audit their environments to identify servers and devices using Intel Ethernet hardware supported by the i40e driver. For critical systems, consider implementing kernel live patching solutions to apply fixes without downtime. Additionally, monitoring kernel logs for Oops messages related to free_irq or i40e driver errors can help detect attempts to trigger this vulnerability. Network device firmware and driver updates from hardware vendors should also be applied as part of a comprehensive patch management strategy. In environments where immediate patching is not feasible, isolating affected systems or limiting access to local users can reduce the risk of exploitation. Finally, incorporating this vulnerability into incident response and vulnerability management workflows will ensure timely detection and remediation.