CVE-2021-47000 is a vulnerability identified in the Linux kernel, specifically related to the Ceph distributed file system component. The issue involves an inode leak occurring during an error condition in the __fh_to_dentry function, which is responsible for converting a file handle to a directory entry. An inode leak means that the kernel fails to properly release inode resources when a getattr operation fails, potentially leading to resource exhaustion over time. This vulnerability does not directly allow for privilege escalation, code execution, or data disclosure, but the improper resource management can degrade system stability and availability. The vulnerability requires local access with low privileges (PR:L) and does not require user interaction (UI:N). The attack vector is local (AV:L), meaning an attacker must have some level of access to the system to exploit it. The CVSS score is 3.3, indicating a low severity impact primarily affecting availability due to potential resource leaks. No known exploits are currently reported in the wild, and the vulnerability has been addressed in recent Linux kernel updates. The affected versions are identified by specific commit hashes, indicating that the fix is integrated into certain kernel revisions. This vulnerability is relevant to systems running Ceph on Linux kernels prior to the patch and could affect environments relying on Ceph for distributed storage.

For European organizations, the primary impact of CVE-2021-47000 lies in potential degradation of system availability in environments using Ceph on Linux. Ceph is widely used in cloud infrastructure, data centers, and enterprise storage solutions, including in sectors such as finance, telecommunications, and public administration across Europe. Resource leaks like inode leaks can cause system instability or crashes if left unpatched, leading to downtime or degraded performance of critical storage services. Although the vulnerability does not compromise confidentiality or integrity, availability issues can disrupt business operations, especially for organizations with high storage demands or those relying on Ceph clusters for critical workloads. The requirement for local access limits the risk from remote attackers but raises concerns about insider threats or compromised internal accounts. Organizations with large-scale Linux deployments using Ceph should prioritize patching to maintain service reliability and prevent potential denial-of-service conditions caused by resource exhaustion.

To mitigate CVE-2021-47000, European organizations should: 1) Identify all Linux systems running Ceph, especially those in production or critical environments. 2) Apply the latest Linux kernel patches that include the fix for this vulnerability, ensuring kernel versions are updated to the commits that resolve the inode leak. 3) Monitor system logs and resource usage metrics for signs of inode leaks or abnormal resource consumption in Ceph-related processes. 4) Implement strict access controls and auditing on systems with Ceph to prevent unauthorized local access, reducing the risk of exploitation by insiders or compromised accounts. 5) Consider deploying automated patch management solutions to ensure timely updates across distributed Linux environments. 6) Test patches in staging environments before production deployment to avoid unintended disruptions. 7) Maintain regular backups and disaster recovery plans to mitigate potential availability impacts from unforeseen issues.