CVE-2021-47319 is a vulnerability identified in the Linux kernel specifically within the virtio-blk driver, which is responsible for handling virtual block devices commonly used in virtualized environments. The issue arises during the suspend/resume procedure of the virtio-blk device. The vulnerability is due to a memory leak caused by improper handling of the vblk->vqs (virtqueue structures) during the restoration process in the virtblk_restore() function. Specifically, the virtqueue pointers are not freed before reinitialization via init_vqs(), leading to a memory leak. This flaw can cause the kernel to consume increasing amounts of memory over time during suspend/resume cycles, potentially leading to resource exhaustion. While this vulnerability does not directly enable code execution or privilege escalation, the memory leak can degrade system stability and availability, especially in environments with frequent suspend/resume operations such as virtual machines or cloud instances. The vulnerability affects specific Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and was publicly disclosed on May 21, 2024. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The fix involves ensuring that the virtqueue structures are properly freed before reinitialization to prevent the leak.

For European organizations, the impact of CVE-2021-47319 primarily concerns system availability and stability rather than direct compromise of confidentiality or integrity. Organizations running Linux-based virtualized infrastructure or cloud services that utilize virtio-blk devices are at risk of memory exhaustion over time if the vulnerability is exploited or triggered by normal suspend/resume operations. This can lead to degraded performance, system crashes, or forced reboots, disrupting business-critical applications and services. Sectors with heavy reliance on virtualization, such as financial services, telecommunications, and cloud service providers, may experience operational disruptions. Although no active exploitation is known, the vulnerability could be leveraged in targeted attacks or combined with other vulnerabilities to amplify impact. The lack of authentication or user interaction requirements means that any process with the ability to trigger suspend/resume cycles on affected systems could inadvertently cause the leak, increasing the risk in multi-tenant or shared environments common in European data centers.

European organizations should promptly apply the available Linux kernel patches that address this memory leak in the virtio-blk driver. Specifically, updating to kernel versions that include the fix for CVE-2021-47319 is critical. For environments where immediate patching is not feasible, administrators should monitor memory usage closely on systems running affected kernel versions, especially those performing frequent suspend/resume cycles. Limiting or controlling suspend/resume operations on virtual machines can reduce exposure. Additionally, organizations should audit their virtualization configurations to ensure virtio-blk devices are used appropriately and consider alternative storage drivers if applicable. Implementing robust monitoring and alerting for unusual memory consumption patterns can help detect exploitation attempts early. Finally, maintaining a strong patch management process and subscribing to Linux kernel security advisories will help mitigate similar vulnerabilities proactively.