CVE-2024-46690 is a vulnerability identified in the Linux kernel's NFS server daemon (nfsd), specifically within the function nfsd4_deleg_getattr_conflict. The issue arises from unsafe dereferencing of the file lock owner's pointer (fl->c.flc_owner) without properly verifying that the file lock operations pointer (fl->fl_lmops) corresponds to the expected lock manager. The vulnerable code tests fl_lmops but largely ignores the result, assuming that flc_owner is always an nfs4_delegation. This assumption is incorrect and can lead to unsafe memory access. The patch restores the previous behavior for cases where fl_lmops is not equal to the nfsd lease manager operations pointer, ensuring that the code does not reference a possible delegation incorrectly. This fix prevents potential memory corruption or crashes caused by dereferencing invalid pointers in the NFSv4 delegation handling code. The vulnerability affects Linux kernel versions identified by the commit hash c5967721e1063648b0506481585ba7e2e49a075e. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability was published on September 13, 2024, and is considered a kernel-level flaw affecting the NFS server component, which is widely used in Linux environments for network file sharing.

For European organizations, the impact of CVE-2024-46690 could be significant, especially for those relying on Linux servers running NFS services for file sharing and storage. Exploitation of this vulnerability could lead to denial of service (system crashes) or potentially memory corruption, which might be leveraged for privilege escalation or arbitrary code execution, depending on the attacker's capabilities and environment. This could disrupt critical business operations, data availability, and integrity, particularly in sectors such as finance, manufacturing, research institutions, and public services that heavily depend on Linux-based infrastructure. Additionally, organizations using NFS for shared storage in cloud or hybrid environments may face increased risk. Since the vulnerability involves kernel-level code, successful exploitation could compromise the entire system's security posture. The absence of known exploits currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits following public disclosure.

European organizations should prioritize applying the official Linux kernel patch that addresses this vulnerability as soon as it becomes available from their Linux distribution vendors. Until patched, organizations should consider the following mitigations: 1) Restrict NFS server access to trusted networks and clients only, using firewall rules and network segmentation to limit exposure. 2) Monitor NFS server logs and system logs for unusual activity or crashes that could indicate exploitation attempts. 3) Employ kernel hardening techniques such as SELinux or AppArmor to limit the impact of potential exploits. 4) Regularly update and audit Linux kernel versions and NFS server configurations to ensure compliance with security best practices. 5) For critical systems, consider temporarily disabling NFS delegation features if feasible, to reduce attack surface. 6) Implement intrusion detection systems (IDS) tuned to detect anomalous NFS traffic patterns. These steps, combined with timely patching, will reduce the risk posed by this vulnerability.