CVE-2021-47257 is a medium-severity vulnerability in the Linux kernel specifically affecting the ieee802154 subsystem, which handles the IEEE 802.15.4 standard for low-rate wireless personal area networks (LR-WPANs). The vulnerability arises from a logic error in the parsing of device addresses within this subsystem. If a user incorrectly sets the mode for a given address type, the kernel code may attempt to dereference a null pointer, leading to a null pointer dereference (CWE-476). This results in a kernel crash or denial of service (DoS) condition. The vulnerability requires local privileges with low complexity (PR:L, AC:L) but does not require user interaction (UI:N). The attack vector is local (AV:L), meaning an attacker must have some level of access to the system to exploit this flaw. The CVSS v3.1 base score is 5.5, reflecting a medium severity primarily due to the impact on availability (A:H) without affecting confidentiality or integrity. No known exploits are currently reported in the wild. The vulnerability was published on May 21, 2024, and affects specific Linux kernel versions identified by commit hashes. The ieee802154 subsystem is not commonly used on typical desktop or server Linux installations but is more relevant in embedded systems, IoT devices, and specialized wireless communication equipment that utilize the IEEE 802.15.4 protocol. Exploitation leads to a kernel panic or system crash, potentially disrupting critical services or embedded device operations. Since the vulnerability is local and requires some privileges, it is less likely to be exploited remotely but could be leveraged by an attacker who has gained limited access to escalate denial-of-service conditions or disrupt device availability. The fix involves correcting the logic error to prevent null pointer dereference during address parsing in the ieee802154 code path.

For European organizations, the impact of CVE-2021-47257 depends largely on their use of Linux-based embedded systems or IoT devices that implement the ieee802154 protocol. Industries such as manufacturing, smart grid utilities, healthcare, and critical infrastructure that deploy wireless sensor networks or low-power wireless communication devices may be affected. A successful exploitation could cause device crashes, leading to service interruptions, operational downtime, and potential safety risks if the affected devices are part of control or monitoring systems. Although the vulnerability does not allow data theft or privilege escalation directly, the denial-of-service impact could disrupt business continuity and critical operations. Given the increasing adoption of IoT and embedded Linux devices in European industrial and smart city environments, this vulnerability could pose a moderate operational risk if unpatched devices are present. However, the requirement for local access and low complexity reduces the likelihood of widespread exploitation in enterprise IT environments. Organizations relying on embedded Linux systems with ieee802154 support should prioritize patching to maintain device availability and avoid potential disruptions.

1. Apply the official Linux kernel patches that address CVE-2021-47257 as soon as they become available from trusted sources or Linux distributions. 2. Identify and inventory all devices and systems running Linux kernels with ieee802154 support, especially embedded and IoT devices, to assess exposure. 3. Restrict local access to affected devices by enforcing strict access controls, limiting user privileges, and monitoring for unauthorized access attempts. 4. Implement network segmentation to isolate critical embedded devices and reduce the risk of an attacker gaining local access. 5. Monitor system logs and kernel crash reports for signs of null pointer dereference or unexpected reboots that could indicate exploitation attempts. 6. For devices that cannot be immediately patched, consider disabling ieee802154 support if it is not required for operational purposes. 7. Engage with device vendors and suppliers to ensure firmware updates incorporating the fix are deployed promptly. 8. Incorporate this vulnerability into vulnerability management and incident response plans to ensure timely detection and remediation.