CVE-2021-47024 is a vulnerability identified in the Linux kernel's vsock/virtio subsystem, which handles communication between virtual machines and the host using virtio sockets. The issue arises from improper handling of queued packets when closing a socket, leading to a memory leak. Specifically, while an initial fix (commit ac03046ece2b) addressed freeing packets during socket release, it failed to fully drain the receive (RX) queue when the socket is definitively closed by scheduled work. This incomplete cleanup results in residual packets remaining in memory, causing a leak. The vulnerability was reported by syzbot, an automated kernel fuzzer, indicating that the issue was found through rigorous automated testing rather than active exploitation. The fix involves using the new function virtio_transport_remove_sock() to drain the RX queue before removing the socket from the af_vsock lists via vsock_remove_sock(), ensuring complete cleanup of queued packets and preventing memory leaks. The affected versions include multiple Linux kernel commits prior to the patch, indicating that the vulnerability affects a range of kernel versions that incorporate the vsock/virtio implementation as it existed before the fix. No known exploits are reported in the wild, and no CVSS score has been assigned yet. The vulnerability primarily impacts systems running Linux kernels with vsock/virtio support, which is commonly used in virtualized environments such as cloud platforms and data centers where guest-to-host communication is required.

For European organizations, the impact of CVE-2021-47024 is primarily related to resource exhaustion and potential denial of service (DoS) conditions on Linux systems running virtualized workloads. Memory leaks can degrade system performance over time, leading to instability or crashes if the leak is significant and persistent. Organizations relying heavily on virtualization technologies (e.g., KVM, QEMU) that utilize vsock for inter-VM or VM-to-host communication may experience degraded service availability or require more frequent system reboots or maintenance to clear leaked memory. While this vulnerability does not directly enable remote code execution or privilege escalation, the resulting instability could disrupt critical services, especially in cloud infrastructure, hosting providers, and enterprises with large-scale virtualized environments. European sectors such as finance, telecommunications, and government services that depend on stable virtualized infrastructure could face operational risks. Additionally, memory leaks can complicate forensic analysis and incident response by obscuring resource usage patterns. However, since no active exploitation is known, the immediate risk is moderate but warrants timely patching to prevent future exploitation or cascading failures.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2021-47024. Specifically, ensure that the kernel incorporates the commit that uses virtio_transport_remove_sock() to properly drain the RX queue. For environments where immediate patching is not feasible, monitoring system memory usage and socket states related to vsock/virtio can help detect abnormal leaks early. Implementing automated alerts for unusual memory consumption on hosts running virtualized workloads is advisable. Additionally, organizations should review their virtualization configurations to minimize unnecessary use of vsock sockets and consider isolating critical workloads to limit impact. Regular kernel updates and integration of security patches into the organization's patch management lifecycle are essential. Testing patches in staging environments before production deployment will reduce operational risks. Finally, maintaining robust backup and recovery procedures will mitigate potential service disruptions caused by memory exhaustion.