CVE-2024-41020 is a vulnerability identified in the Linux kernel related to the file locking mechanism, specifically involving the fcntl/close race condition in the filelock subsystem. The issue arises from a race condition between the fcntl system call, which manages file locks, and the close system call, which releases file descriptors. The vulnerability was initially addressed in a prior commit (3cad1bc01041) that aimed to reliably remove locks when this race condition is detected. However, the fix was incomplete because it only covered the normal code path and neglected the compatibility path used for 64-bit offsets on 32-bit kernels. This oversight means that on 32-bit Linux kernels using 64-bit file offsets, the race condition could still be exploited. The vulnerability allows for potential inconsistencies in file locking state, which could lead to improper lock removal or retention, potentially causing data corruption, denial of service, or unauthorized access to files due to stale locks. The patch now applies the same fix to the compatibility path, closing this gap. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability affects Linux kernels identified by the commit hash c293621bbf678a3d85e3ed721c3921c8a670610d and similar versions that include the unpatched code. This issue is subtle and primarily affects systems running 32-bit kernels with 64-bit offset support, which are less common but still present in certain environments.

For European organizations, the impact of CVE-2024-41020 depends on their use of Linux systems, particularly those running 32-bit kernels with 64-bit offset support. While many modern systems have moved to 64-bit architectures, legacy systems and embedded devices may still operate on 32-bit kernels. The vulnerability could lead to data integrity issues due to improper file locking, potentially causing application errors, data corruption, or denial of service if critical files are improperly locked or unlocked. In multi-user or multi-process environments, this could allow unauthorized processes to access files that should be locked, increasing the risk of data leakage or unauthorized modification. Although no active exploitation is reported, the presence of this race condition could be leveraged by attackers with local access to escalate privileges or disrupt services. European sectors with critical infrastructure, financial services, or government systems relying on Linux-based servers or embedded devices could face operational disruptions or data integrity risks if unpatched. The risk is heightened in environments where file locking is critical for application correctness, such as database servers, file servers, or systems managing concurrent file access.

European organizations should prioritize patching Linux kernels to include the fix for CVE-2024-41020, especially on systems running 32-bit kernels with 64-bit offset support. Since the vulnerability arises from a race condition in file locking, updating to the latest stable kernel versions that incorporate the patch is the most effective mitigation. For legacy or embedded systems where kernel upgrades are challenging, organizations should audit and limit local user access to trusted personnel only, as exploitation requires local access. Additionally, monitoring file locking behavior and system logs for anomalies related to fcntl and close system calls can help detect potential exploitation attempts. Implementing application-level safeguards to verify file lock states before critical operations may reduce impact. Organizations should also review their inventory to identify systems running affected kernel versions and prioritize remediation accordingly. Finally, maintaining a robust patch management process and subscribing to Linux kernel security advisories will ensure timely awareness and response to similar vulnerabilities.