CVE-2021-47224 is a medium-severity vulnerability in the Linux kernel's network driver code, specifically within the ll_temac driver responsible for handling Ethernet MAC (Media Access Control) operations. The vulnerability arises from improper management of socket buffer (skb) memory during transmission. In the affected code, the skb pointer is piggy-backed on the transmit buffer descriptor (TX BD) to efficiently free the skb buffer once the frame transmission completes. However, the implementation incorrectly frees the skb when the first TX BD of a multi-BD packet is completed, even though other fragments of the skb are still in use. This results in a use-after-free condition on the DMA (Direct Memory Access) side, where the memory buffer is freed prematurely while still being accessed by ongoing transmission operations. Such a use-after-free can lead to undefined behavior, including potential kernel crashes or memory corruption. The vulnerability does not impact confidentiality or integrity directly but affects availability due to possible kernel panics or system instability. Exploitation requires local access (AV:L - Attack Vector: Local) but no privileges (PR:N) or user interaction (UI:N) are needed, making it somewhat easier for local attackers to trigger. The vulnerability was fixed by ensuring the skb is freed only after all TX BDs associated with the skb are processed, preventing premature freeing and use-after-free conditions.

For European organizations, the impact of CVE-2021-47224 primarily concerns system availability and stability. Linux is widely deployed across European enterprises, government agencies, and critical infrastructure, often powering servers, network devices, and embedded systems. Systems running affected versions of the Linux kernel with the vulnerable ll_temac driver could experience kernel crashes or instability if exploited, leading to denial of service conditions. This could disrupt business operations, network communications, or critical services, especially in environments relying on embedded Linux devices or specialized network hardware using the ll_temac driver. Although the vulnerability does not allow privilege escalation or data leakage, the resulting downtime or system instability could have significant operational and financial consequences. The lack of known exploits in the wild reduces immediate risk, but organizations should remain vigilant and patch promptly to prevent potential future exploitation.

European organizations should take the following specific mitigation steps: 1) Identify all Linux systems running kernels with the vulnerable ll_temac driver, particularly embedded devices or network appliances using this driver. 2) Apply the official Linux kernel patches that fix CVE-2021-47224 as soon as they become available from trusted sources or vendor distributions. 3) For devices where kernel upgrades are not immediately feasible, consider isolating or limiting local access to reduce the risk of local exploitation. 4) Monitor system logs and kernel messages for signs of instability or crashes related to network transmission. 5) Engage with hardware vendors or Linux distribution maintainers to confirm patch availability and deployment timelines. 6) Implement robust system integrity monitoring to detect anomalous behavior that could indicate exploitation attempts. 7) Incorporate this vulnerability into vulnerability management and incident response plans to ensure timely detection and remediation.