CVE-2021-47320 is a vulnerability identified in the Linux kernel's NFS (Network File System) implementation, specifically related to the handling of POSIX ACLs (Access Control Lists) in the functions posix_acl_create(), nfs3_proc_create(), and nfs3_proc_mknod(). The issue involves a memory leak where ACL and default ACL objects are not properly freed in certain error paths during NFSv3 create and mknod operations. This leak occurs when the kernel encounters errors while processing these NFS operations, leading to unreleased memory allocations associated with ACL structures. Although the vulnerability does not directly allow for code execution or privilege escalation, the memory leak can degrade system performance over time, potentially leading to resource exhaustion on systems heavily utilizing NFS with ACLs. The vulnerability was discovered through testing with NFS xfstests and has been addressed by fixing the error handling paths to ensure proper cleanup of ACL memory allocations. No known exploits are currently reported in the wild, and no CVSS score has been assigned. The affected versions are identified by a specific commit hash, indicating that this issue pertains to certain Linux kernel versions prior to the patch. The fix involves correcting the kernel code to prevent ACL memory leaks during error handling in NFSv3 operations.

For European organizations, the impact of CVE-2021-47320 primarily concerns environments that rely heavily on Linux-based NFS servers with POSIX ACLs enabled. Organizations with large-scale file sharing and storage infrastructures, such as research institutions, cloud service providers, and enterprises using NFS for distributed file systems, may experience gradual degradation of system stability and performance due to memory leaks. Over time, this could lead to increased system crashes or the need for unplanned reboots, affecting availability and operational continuity. While the vulnerability does not directly compromise confidentiality or integrity, the potential for denial of service through resource exhaustion could disrupt critical services. European organizations with compliance requirements for high availability and data integrity should consider this risk significant, especially in sectors like finance, healthcare, and government where Linux servers are prevalent. The absence of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation or operational issues.

To mitigate this vulnerability, European organizations should: 1) Identify Linux systems running affected kernel versions, particularly those acting as NFS servers with POSIX ACLs enabled. 2) Apply the latest Linux kernel patches or updates that include the fix for CVE-2021-47320 as soon as they become available from trusted Linux distribution vendors. 3) Monitor system memory usage and logs for signs of abnormal memory consumption or leaks related to NFS operations. 4) Where immediate patching is not feasible, consider temporarily disabling POSIX ACL support on NFS shares if this does not disrupt business operations. 5) Implement robust system monitoring and alerting to detect early signs of resource exhaustion. 6) Regularly audit and test NFS configurations and ACL usage to ensure they follow best practices and minimize unnecessary complexity. 7) Engage with Linux vendor security advisories and subscribe to relevant security mailing lists to stay informed about updates and potential exploit developments.