CVE-2021-39977 is a high-severity vulnerability identified in Huawei's HarmonyOS version 2.0, specifically within the HwNearbyMain module. The vulnerability is classified as a NULL Pointer Dereference (CWE-476), which occurs when the software attempts to read or write to a memory location through a pointer that has a NULL value. This leads to an invalid memory access that causes the affected process to crash and subsequently restart. The vulnerability does not require any privileges or user interaction to be exploited, and it can be triggered remotely over the network (AV:N/AC:L/PR:N/UI:N). The impact is limited to availability, as the vulnerability does not compromise confidentiality or integrity but causes a denial-of-service condition by forcing the process to restart. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the ease of exploitation and the potential disruption caused. No known exploits have been reported in the wild, and no official patches or mitigation links were provided at the time of publication. The vulnerability affects HarmonyOS 2.0, an operating system primarily deployed on Huawei devices, including smartphones, IoT devices, and other smart hardware. The HwNearbyMain module likely handles nearby device communication or discovery services, so exploitation could disrupt these functionalities.

For European organizations, the primary impact of this vulnerability is the potential disruption of services running on Huawei HarmonyOS devices. Organizations that deploy Huawei smartphones, IoT devices, or other smart devices using HarmonyOS could experience denial-of-service conditions affecting device availability and reliability. This could impact operational continuity, especially in environments relying on Huawei hardware for communication or IoT management. While the vulnerability does not expose sensitive data or allow unauthorized access, the forced process restarts could degrade user experience and interrupt critical workflows. In sectors such as manufacturing, smart cities, or telecommunications where Huawei devices might be integrated, this could lead to temporary outages or degraded service quality. However, since no known exploits are reported in the wild, the immediate risk is moderate but warrants proactive mitigation to prevent future exploitation.

Given the absence of official patches, European organizations should implement specific mitigations to reduce exposure. First, conduct an inventory to identify all Huawei HarmonyOS 2.0 devices within the network, focusing on those running the HwNearbyMain module. Limit network exposure of these devices by segmenting them into isolated VLANs or network zones with strict access controls to prevent unauthorized remote triggering of the vulnerability. Employ network-level intrusion detection systems (IDS) to monitor for anomalous traffic patterns targeting the HwNearbyMain service. Disable or restrict the HwNearbyMain module functionality if it is not essential for business operations to reduce the attack surface. Engage with Huawei support channels to obtain any available patches or updates and apply them promptly once released. Additionally, implement robust device monitoring to detect frequent process restarts or crashes indicative of exploitation attempts. For critical environments, consider deploying alternative hardware or OS platforms until the vulnerability is fully remediated.