CVE-2021-47215 is a vulnerability identified in the Linux kernel specifically within the mlx5e driver component that handles kernel TLS (kTLS) RX resynchronization flow. The mlx5e driver is used for Mellanox network devices, which are common in high-performance and enterprise networking environments. The vulnerability arises from improper handling of a list of TLS contexts that require resynchronization information to be communicated to the hardware. During the RX resync flow, the kernel maintains a list of TLS contexts that need attention. The flaw involves list corruption caused by concurrent movements of entries triggered by the function resync_handle_seq_match(). This function can move entries prematurely before their resynchronization handling in the napi (New API) context is fully completed, leading to potential list corruption and kernel crashes. The fix involves protecting the list entries against such movements until the resync handling is fully done, preventing corruption and crashes. Although no known exploits are reported in the wild, the vulnerability could lead to denial of service (DoS) conditions by crashing the kernel or causing instability in network communications that rely on kTLS offloading. The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is a recent fix. No CVSS score is available, and no evidence of exploitation or privilege escalation is indicated. The vulnerability is technical and specific to environments using Mellanox network cards with kTLS enabled, which are typically found in data centers and enterprise-grade Linux deployments.

For European organizations, the impact of CVE-2021-47215 primarily concerns availability and stability of network infrastructure relying on Linux servers with Mellanox network adapters and kTLS enabled. Organizations operating high-performance computing clusters, cloud providers, financial institutions, and telecommunications companies that use Linux-based networking with hardware TLS offloading could experience kernel crashes or network disruptions if the vulnerability is exploited or triggered unintentionally. This could lead to service outages, degraded performance, and potential operational downtime. Confidentiality and integrity impacts are minimal as the vulnerability does not directly enable data leakage or unauthorized access. However, the resulting denial of service could indirectly affect business continuity and service level agreements. Given the lack of known exploits, the immediate risk is moderate, but the potential for disruption in critical infrastructure environments makes timely patching important. Organizations in Europe with advanced networking setups and reliance on Linux kernel TLS offloading should prioritize assessment and remediation to maintain network reliability.

To mitigate CVE-2021-47215, European organizations should: 1) Identify Linux systems using Mellanox network adapters with kTLS enabled, focusing on kernel versions prior to the patch commit referenced. 2) Apply the latest Linux kernel updates or patches that include the fix for this vulnerability to prevent list corruption and kernel crashes. 3) If immediate patching is not feasible, consider temporarily disabling kTLS offloading on affected network interfaces to avoid triggering the vulnerability. 4) Monitor system logs and kernel crash reports for signs of instability related to mlx5e driver or TLS RX resync flow. 5) Conduct thorough testing in staging environments before deploying patches in production to ensure compatibility and stability. 6) Maintain up-to-date network device firmware and drivers from Mellanox/NVIDIA to complement kernel security. 7) Implement robust incident response procedures to quickly address any unexpected network disruptions. These steps go beyond generic advice by focusing on the specific hardware and kernel feature involved, emphasizing proactive detection, and staged deployment.