CVE-2024-53210 is a vulnerability identified in the Linux kernel specifically affecting the s390 architecture's IUCV (Inter-User Communication Vehicle) socket implementation. The issue arises when the MSG_PEEK flag is passed to the skb_recv_datagram() function. Normally, MSG_PEEK allows a process to look at incoming data without removing it from the queue. However, in this case, passing MSG_PEEK increments the socket buffer's (skb) reference count (skb->users), but the corresponding decrement operation is missing in the iucv_sock_recvmsg() function upon exit. This imbalance causes a memory leak because the reference count remains artificially high, preventing the skb memory from being freed during skb_queue_purge(). Additionally, this leads to a WARN_ON condition in iucv_sock_destruct() when the socket is closed, indicating an abnormal state. The vulnerability is rooted in the failure to properly manage the skb reference count lifecycle when MSG_PEEK is used, which can cause resource exhaustion over time. The vulnerability is specific to the s390 architecture (IBM mainframe systems) running Linux kernel versions prior to the fix. The fix involves decrementing the skb reference count by one when MSG_PEEK is set, preventing the memory leak and the WARN_ON warning during socket destruction. The vulnerability was disclosed and published in late December 2024, with no known exploits in the wild at the time of reporting. The technical details and call trace indicate the problem occurs in the af_iucv kernel module, which handles IUCV sockets on s390 systems. This is a low-level kernel memory management bug affecting socket operations on a niche platform.

For European organizations, the impact of CVE-2024-53210 is primarily relevant to those operating IBM mainframe systems running Linux on the s390 architecture, which is less common than x86 or ARM architectures. The vulnerability causes a memory leak in kernel socket buffers when using MSG_PEEK on IUCV sockets, potentially leading to gradual resource exhaustion and degraded system performance or stability. Over time, this could cause denial of service conditions on affected systems if the leak is exploited or triggered repeatedly. However, there is no indication that this vulnerability leads to privilege escalation, arbitrary code execution, or direct data compromise. The impact is therefore mostly on availability and system reliability rather than confidentiality or integrity. Organizations relying on s390 Linux systems for critical workloads, such as financial institutions, government agencies, or large enterprises in Europe, could experience operational disruptions if the vulnerability is not patched. Since no known exploits exist yet, the immediate risk is low, but the vulnerability should be addressed proactively to prevent potential future exploitation or accidental system degradation.

1. Apply the official Linux kernel patch that decrements the skb reference count when MSG_PEEK is used on IUCV sockets. This patch is the definitive fix and should be deployed as soon as it is available for your kernel version. 2. If patching is not immediately possible, monitor system logs for WARN_ON messages related to iucv_sock_destruct() and track memory usage trends on s390 Linux hosts to detect abnormal increases that could indicate the leak is being triggered. 3. Limit or audit the use of MSG_PEEK flag on IUCV sockets in applications running on s390 Linux systems to reduce the likelihood of triggering the leak. 4. Implement resource limits and socket usage monitoring to prevent resource exhaustion from impacting system availability. 5. Coordinate with IBM and Linux kernel maintainers for updated kernel versions and backports relevant to your environment. 6. Conduct regular vulnerability assessments and kernel updates as part of your patch management lifecycle, especially for niche architectures like s390 where vulnerabilities may be less publicized.