CVE-2021-39983 is a high-severity vulnerability identified in the HwNearbyMain module of Huawei's HarmonyOS version 2.0. This vulnerability arises from data processing errors within the module, which can be triggered remotely without requiring any privileges or user interaction. Exploitation of this flaw can cause the affected process to restart, leading to a denial-of-service (DoS) condition. The Common Vulnerability Scoring System (CVSS) v3.1 score of 7.5 reflects the significant impact on availability, with no direct impact on confidentiality or integrity. The attack vector is network-based (AV:N), and the vulnerability is exploitable with low complexity (AC:L), requiring no privileges (PR:N) or user interaction (UI:N). The scope remains unchanged (S:U), meaning the vulnerability affects only the vulnerable component without impacting other system components. Although no known exploits have been reported in the wild, the potential for disruption exists, especially in environments where HarmonyOS devices are integrated into critical workflows or infrastructure. The lack of available patches at the time of reporting increases the urgency for mitigation and monitoring. Given that the vulnerability causes process restarts, repeated exploitation could degrade system reliability and availability, potentially impacting user experience and operational continuity.

For European organizations, the impact of CVE-2021-39983 depends largely on the deployment scale of Huawei HarmonyOS devices within their environments. While HarmonyOS is primarily targeted at consumer electronics and IoT devices, its increasing adoption in smart devices and potentially in enterprise contexts means that affected organizations could face service disruptions. The denial-of-service effect caused by process restarts could interrupt critical device functions, leading to operational downtime or degraded service quality. In sectors such as telecommunications, manufacturing, or smart city infrastructure where Huawei devices might be integrated, this vulnerability could affect system stability and reliability. Additionally, organizations relying on HarmonyOS-based devices for remote monitoring or control could experience interruptions, impacting business continuity. Although the vulnerability does not compromise data confidentiality or integrity, the availability impact alone can have significant operational consequences, especially in environments requiring high uptime and reliability.

Given the absence of official patches at the time of reporting, European organizations should implement specific mitigations to reduce exposure. First, network-level controls should be enforced to restrict access to HarmonyOS devices, limiting communication to trusted sources and segments. Deploying network segmentation and firewall rules can reduce the attack surface. Continuous monitoring of device logs and network traffic for anomalies indicative of exploitation attempts is critical. Organizations should also maintain an inventory of HarmonyOS devices to assess exposure and prioritize risk management. Where possible, disabling or restricting the HwNearbyMain module or related services could mitigate the vulnerability's impact, though this may affect device functionality and should be tested carefully. Engaging with Huawei for updates and patches is essential, and organizations should plan for timely deployment once available. Additionally, implementing redundancy and failover mechanisms can help maintain service availability in case of device restarts triggered by exploitation attempts.