CVE-2022-48977 is a vulnerability identified in the Linux kernel's Controller Area Network (CAN) subsystem, specifically within the af_can module responsible for CAN frame reception filtering. The issue arises from a NULL pointer dereference in the can_rcv_filter function. This vulnerability is analogous to a previously addressed issue in can_rx_register(), where a missing initialization of the ml_priv pointer led to similar problems. The root cause is that since commit 4e096a18867a ("net: introduce CAN specific pointer in the struct net_device"), the existing check for device type (dev->type) being ARPHRD_CAN is insufficient. This is because other network devices, such as bonding or tun devices, may claim to be CAN devices but do not initialize the ml_priv pointer accordingly. As a result, when the CAN receive path processes frames from these devices, it may dereference a NULL pointer, leading to a kernel crash (denial of service) or potential system instability. The affected Linux kernel versions include multiple commits around the 4e096a18867a change, indicating that this vulnerability has been present since that commit was introduced. No known exploits are reported in the wild yet, and no CVSS score has been assigned. The vulnerability impacts the kernel's network stack, specifically CAN protocol handling, which is used in automotive, industrial control, and embedded systems. The issue is technical and requires kernel-level understanding to exploit or mitigate.

For European organizations, the impact of CVE-2022-48977 depends largely on their use of Linux systems that utilize the CAN protocol, which is common in automotive manufacturing, industrial automation, and embedded device environments. A successful exploitation leads to a NULL pointer dereference causing a kernel panic or system crash, resulting in denial of service (DoS). This can disrupt critical operations, especially in sectors relying on real-time CAN communications such as automotive production lines, transportation infrastructure, and industrial control systems. The vulnerability could cause operational downtime, loss of productivity, and potentially safety risks if embedded systems controlling machinery or vehicles are affected. While no remote code execution or privilege escalation is indicated, the DoS impact on availability is significant. European organizations with Linux-based CAN-enabled devices or infrastructure should consider this vulnerability a risk to system stability and continuity of operations. Given the lack of known exploits, the immediate threat may be low, but the potential for disruption in critical sectors is notable.

To mitigate CVE-2022-48977, organizations should: 1) Apply the latest Linux kernel patches that address the NULL pointer dereference in the af_can module as soon as they become available from trusted Linux distributions or kernel maintainers. 2) Audit and inventory Linux systems that utilize CAN networking, especially embedded or industrial devices, to identify potentially vulnerable kernel versions. 3) Where patching is not immediately feasible, consider isolating CAN-enabled Linux systems from untrusted networks to reduce exposure. 4) Implement monitoring for kernel crashes or unusual CAN network behavior that could indicate exploitation attempts or instability. 5) Collaborate with device vendors to ensure embedded Linux systems receive timely updates. 6) For development environments, review custom kernel modules or network device configurations to ensure proper initialization of ml_priv pointers and adherence to updated kernel APIs. 7) Conduct thorough testing of CAN-related functionality after patching to confirm stability and correct operation. These steps go beyond generic advice by focusing on CAN-specific network device configurations and embedded system considerations.