CVE-2021-47470 is a vulnerability identified in the Linux kernel's memory management subsystem, specifically related to the slab allocator's debug filesystem operations. The issue arises in the handling of slab cache objects within the kernel's slab debugging infrastructure. When the function sysfs_slab_add fails, the code erroneously proceeds to call debugfs_slab_add() on a slab cache object 's' that is about to be freed. Subsequently, slab_debugfs_fops, which operates on this slab cache object, attempts to use 's' after it has been freed, leading to a use-after-free condition. Use-after-free vulnerabilities occur when a program continues to use a pointer after the memory it points to has been deallocated, potentially leading to undefined behavior, including memory corruption, crashes, or arbitrary code execution. This vulnerability is rooted in a logic error in the kernel's slab debugging code path, which can be triggered during slab cache management operations. Although no known exploits are currently reported in the wild, the vulnerability could be leveraged by a local attacker or malicious process with the ability to trigger slab cache operations to cause denial of service or potentially escalate privileges by exploiting kernel memory corruption. The affected versions correspond to specific Linux kernel commits prior to the fix. The vulnerability was published on May 22, 2024, and no CVSS score has been assigned yet. The fix involves ensuring that debugfs_slab_add() is not called if sysfs_slab_add fails, preventing the use-after-free scenario.

For European organizations, the impact of CVE-2021-47470 depends largely on the deployment of vulnerable Linux kernel versions within their infrastructure. Since Linux is widely used in servers, cloud environments, embedded devices, and critical infrastructure, this vulnerability could affect a broad range of systems. Exploitation could lead to kernel crashes causing denial of service, which may disrupt business operations, especially for service providers and enterprises relying on Linux-based servers. More critically, if an attacker can leverage the use-after-free to execute arbitrary code in kernel space, this could lead to privilege escalation, allowing attackers to gain root access and compromise system integrity and confidentiality. This poses significant risks to data protection and operational continuity, particularly in sectors such as finance, healthcare, telecommunications, and government agencies across Europe. The absence of known exploits reduces immediate risk, but the vulnerability's nature warrants prompt attention to prevent future exploitation. Organizations using Linux in sensitive or critical environments should prioritize patching to mitigate potential exploitation vectors.

To mitigate CVE-2021-47470, European organizations should: 1) Identify all Linux systems running kernel versions prior to the patch that addresses this vulnerability. 2) Apply the official kernel updates or patches provided by their Linux distribution vendors promptly. Since the vulnerability is in the kernel's slab debugging code, disabling slab debugging features (if enabled and not required) can reduce the attack surface temporarily. 3) Implement strict access controls to limit unprivileged users' ability to trigger slab cache operations or load kernel modules, reducing the likelihood of exploitation. 4) Monitor system logs and kernel messages for unusual slab cache activity or crashes that could indicate attempted exploitation. 5) Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR), Kernel Page Table Isolation (KPTI), and other security modules (e.g., SELinux, AppArmor) to increase the difficulty of successful exploitation. 6) Maintain an up-to-date inventory of Linux kernel versions and automate patch management to ensure timely remediation of vulnerabilities. 7) For critical systems, consider deploying intrusion detection systems capable of monitoring kernel-level anomalies.