CVE-2024-46801 is a recently disclosed vulnerability in the Linux kernel affecting the libfs component, specifically the function get_stashed_dentry(). This function attempts to optimistically retrieve a stashed dentry (directory entry) from a given memory location. The vulnerability arises because get_stashed_dentry() did not properly ensure that the Read-Copy-Update (RCU) lock was held before dereferencing the stashed pointer, leading to a potential use-after-free (UAF) condition. The fix involves replacing the READ_ONCE() macro with rcu_dereference(), which not only provides the necessary RCU protection but also includes lock dependency (lockdep) checks to prevent such concurrency issues. The use-after-free vulnerability could allow an attacker to cause memory corruption by accessing freed memory, potentially leading to kernel crashes or privilege escalation if exploited. However, as of the publication date, there are no known exploits in the wild targeting this vulnerability. The affected Linux kernel versions are identified by specific commit hashes, indicating this is a recent code-level issue addressed in the kernel source. The vulnerability is rooted in concurrency control and memory safety within the kernel's filesystem handling code, which is critical for system stability and security.

For European organizations, the impact of CVE-2024-46801 depends largely on their use of Linux-based systems, particularly those running vulnerable kernel versions. Since Linux is widely deployed across servers, cloud infrastructure, embedded devices, and desktops in Europe, the vulnerability could affect a broad range of environments. Exploitation could lead to denial of service via kernel crashes or potentially privilege escalation, allowing attackers to gain unauthorized root access. This could compromise confidentiality, integrity, and availability of critical systems, especially in sectors like finance, healthcare, government, and telecommunications that rely heavily on Linux servers. Given the kernel-level nature of the flaw, successful exploitation could undermine the security of containerized environments and virtualized infrastructures common in European data centers. Although no active exploits are known, the vulnerability's presence in core kernel code means that attackers with local access could attempt to leverage it for lateral movement or persistence. The impact is heightened in environments where kernel updates are delayed or where systems run custom or long-term support kernels without timely patching.

European organizations should prioritize applying the official Linux kernel patches that replace READ_ONCE() with rcu_dereference() in the get_stashed_dentry() function. Kernel updates should be deployed promptly, especially on production servers and critical infrastructure. Organizations using long-term support (LTS) kernels should monitor vendor advisories for backported fixes. Additionally, implementing strict access controls to limit local user privileges can reduce the risk of exploitation, as local code execution is typically required. Employing kernel hardening features such as Kernel Page Table Isolation (KPTI), SELinux/AppArmor policies, and secure boot can further mitigate risks. Continuous monitoring for unusual kernel crashes or suspicious local activity is recommended. For environments using containerization or virtualization, ensure host kernels are patched to prevent container breakout attacks. Finally, organizations should integrate this vulnerability into their vulnerability management and patching workflows to maintain timely remediation.