CVE-2025-21774 is a vulnerability identified in the Linux kernel, specifically within the CAN (Controller Area Network) driver for Rockchip hardware, in the function rkcanfd_handle_rx_fifo_overflow_int(). The issue arises from improper handling of a NULL pointer condition when the socket buffer (skb) cannot be allocated during a receive FIFO overflow interrupt. The vulnerability is due to a missing or incorrect NULL pointer check, which could lead to a kernel crash or undefined behavior if the system attempts to dereference a NULL skb pointer. The fix involves adding a proper bail-out mechanism in the function to safely handle the failure to allocate skb, preventing potential kernel panics or memory corruption. This vulnerability affects Linux kernel versions identified by the given commit hashes, indicating it is present in certain recent kernel builds prior to the patch. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability is rooted in kernel-level code, which operates with high privileges and is critical for system stability and security.

For European organizations, the impact of this vulnerability could be significant, especially for those relying on Linux-based systems running on Rockchip hardware or embedded devices using the affected CAN driver. Exploitation could lead to denial of service via kernel crashes, potentially disrupting critical infrastructure, industrial control systems, or automotive systems that use CAN communication. Since the Linux kernel is widely used across servers, desktops, and embedded devices, any instability or crashes caused by this vulnerability could affect availability and reliability of services. While there is no evidence of remote code execution or privilege escalation directly from this flaw, the resulting kernel panic could be leveraged in targeted denial-of-service attacks. Organizations in sectors such as manufacturing, automotive, telecommunications, and IoT deployments in Europe may be particularly at risk if their systems incorporate the affected Rockchip CAN driver. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed promptly to maintain system integrity and availability.

To mitigate this vulnerability, European organizations should: 1) Identify systems running Linux kernels with the affected Rockchip CAN driver, particularly those using CAN FD interfaces. 2) Apply the latest Linux kernel patches or updates that include the fix for CVE-2025-21774 as soon as they become available. 3) For embedded or specialized devices, coordinate with hardware vendors or device manufacturers to obtain firmware updates incorporating the patched kernel. 4) Implement monitoring for kernel crashes or unusual system behavior that could indicate attempts to trigger this vulnerability. 5) In environments where patching is delayed, consider isolating affected devices from critical networks or limiting CAN traffic to reduce the risk of triggering the overflow condition. 6) Conduct thorough testing of updated kernels in staging environments to ensure stability before deployment. 7) Maintain an inventory of Linux kernel versions and hardware platforms to quickly identify vulnerable systems in the future.