CVE-2021-47466 is a vulnerability identified in the Linux kernel's memory management subsystem, specifically within the SLUB allocator component. The issue arises in the function kmem_cache_open(), which is responsible for managing kernel memory caches. In certain error paths, the random_seq data structure associated with the SLUB cache may not be properly released, leading to a potential memory leak. This leak occurs because the cleanup routine does not invoke __kmem_cache_release() to free all related resources, allowing kernel memory to be consumed unnecessarily over time. While the vulnerability does not directly enable code execution or privilege escalation, the improper resource management can degrade system stability and performance, especially on systems with long uptimes or heavy memory allocation demands. The fix involves ensuring that __kmem_cache_release() is called in all error paths to properly release the random_seq and other associated resources, preventing the leak. The vulnerability affects specific Linux kernel versions identified by commit hashes, and no known exploits are currently reported in the wild. No CVSS score has been assigned yet, but the issue is recognized and patched by the Linux project as of May 22, 2024.

For European organizations, the impact of CVE-2021-47466 primarily concerns system reliability and availability rather than direct data confidentiality or integrity breaches. Servers and infrastructure running affected Linux kernel versions may experience gradual memory exhaustion due to the leak, potentially leading to degraded performance, increased latency, or even system crashes if the leak is severe and unmitigated. This can disrupt critical services, especially in sectors relying heavily on Linux-based systems such as finance, telecommunications, cloud providers, and public sector IT infrastructure. Although exploitation does not appear to allow remote code execution or privilege escalation, the indirect effects on availability could cause operational disruptions and increased maintenance overhead. Organizations with high uptime requirements or those running embedded Linux devices may be particularly vulnerable to the cumulative effects of this leak. Since no active exploits are known, the immediate risk is moderate, but unpatched systems remain exposed to potential future exploitation or stability issues.

To mitigate CVE-2021-47466, European organizations should promptly apply the official Linux kernel patches that address the memory leak in kmem_cache_open(). System administrators should: 1) Identify all Linux systems running affected kernel versions by verifying kernel commit hashes or version numbers; 2) Schedule and perform kernel updates during maintenance windows to minimize service disruption; 3) Monitor system memory usage trends closely on critical servers to detect abnormal memory consumption patterns indicative of leaks; 4) Employ automated configuration management and patch deployment tools to ensure consistent and timely updates across infrastructure; 5) For embedded or specialized devices where kernel updates may be delayed, consider implementing memory usage alerts and periodic reboots as interim mitigations; 6) Review and test kernel updates in staging environments to verify stability and compatibility before production deployment. Additionally, maintain up-to-date backups and incident response plans to address any unforeseen stability issues arising from the vulnerability.