CVE-2021-39985 is a high-severity vulnerability identified in Huawei's HarmonyOS version 2.0, specifically within the HwNearbyMain module. The vulnerability arises from improper validation of array indices (classified under CWE-129), which can lead to out-of-bounds access. This flaw allows an attacker to supply crafted input that causes the system to access invalid memory locations. The primary consequence of exploiting this vulnerability is a denial-of-service (DoS) condition, where the affected process restarts unexpectedly. The vulnerability does not impact confidentiality or integrity but affects availability by disrupting normal operation. The CVSS v3.1 score of 7.5 reflects the ease of exploitation (network attack vector, no privileges or user interaction required) and the significant impact on availability. No known exploits are currently reported in the wild, and no official patches have been linked, indicating that mitigation may rely on vendor updates or workarounds. The vulnerability's network attack vector and lack of required privileges make it a notable risk for devices running HarmonyOS, especially those exposed to untrusted networks or inputs processed by the HwNearbyMain module.

For European organizations, the impact of CVE-2021-39985 primarily concerns availability disruptions in devices running HarmonyOS 2.0. Huawei's HarmonyOS is increasingly deployed in IoT devices, smartphones, and smart home products, some of which may be integrated into enterprise environments or critical infrastructure. A successful exploitation could cause service interruptions, leading to operational downtime or degraded user experience. While the vulnerability does not compromise data confidentiality or integrity, the forced process restarts could interrupt automated workflows, monitoring systems, or communication channels reliant on affected devices. Organizations in sectors such as telecommunications, manufacturing, and smart city deployments that utilize Huawei HarmonyOS-based devices may face increased risk. Additionally, the lack of known exploits currently reduces immediate threat but does not eliminate the risk of future exploitation, especially as attackers develop proof-of-concept code.

To mitigate CVE-2021-39985, European organizations should: 1) Monitor Huawei's official security advisories and promptly apply any patches or firmware updates addressing this vulnerability once released. 2) Implement network segmentation to isolate HarmonyOS devices, limiting exposure to untrusted networks and reducing the attack surface. 3) Employ strict input validation and filtering at network boundaries to prevent malformed or malicious data from reaching the HwNearbyMain module. 4) Where possible, disable or restrict the HwNearbyMain module or related services if they are not essential to device operation. 5) Conduct regular device inventory and vulnerability assessments to identify and prioritize vulnerable HarmonyOS devices for remediation. 6) Collaborate with Huawei support channels to obtain guidance on interim mitigations and monitor for emerging exploit techniques. These steps go beyond generic advice by focusing on network controls, device management, and vendor coordination specific to the affected product and module.