CVE-2025-66329 is a permission control vulnerability categorized under CWE-264, affecting the window management module of Huawei's HarmonyOS. The vulnerability arises from improper enforcement of access controls, allowing unauthorized local attackers to interfere with the availability of the system. Specifically, the flaw permits an attacker without privileges or user interaction to trigger conditions that degrade or deny service on affected devices. The vulnerability spans multiple HarmonyOS versions, including 2.0.0 through 4.3.1, indicating a long-standing issue across several releases. The CVSS 3.1 base score is 4.0, reflecting a medium severity primarily due to its limited attack vector (local access required) and lack of impact on confidentiality or integrity. There are no known exploits in the wild, and no patches have been released as of the publication date (December 8, 2025). The vulnerability could be exploited by malicious local users or malware with local execution capabilities to cause denial-of-service conditions by manipulating window management functions, potentially leading to system instability or crashes. This could disrupt device availability, impacting user productivity and service continuity. The lack of required privileges or user interaction lowers the barrier for exploitation once local access is obtained, but remote exploitation is not feasible. The vulnerability highlights the importance of robust permission checks in critical OS modules to prevent unauthorized interference with system operations.

For European organizations, the primary impact of CVE-2025-66329 is the potential disruption of device availability, which could affect business continuity, especially in environments relying on Huawei HarmonyOS-powered devices for critical operations. Although the vulnerability does not compromise data confidentiality or integrity, denial-of-service conditions could interrupt workflows, degrade user experience, and increase operational costs due to downtime or recovery efforts. Organizations with Huawei smartphones, IoT devices, or embedded systems running affected HarmonyOS versions may face risks if local attackers or malware gain access. This is particularly relevant for sectors with high device usage density, such as telecommunications, manufacturing, and public services. The absence of known exploits reduces immediate risk, but the vulnerability could be leveraged in targeted attacks or insider threat scenarios. Additionally, the medium severity score suggests that while the impact is limited, it should not be ignored, especially in environments where device availability is critical. European entities involved in supply chain operations or infrastructure using Huawei technology should prioritize awareness and readiness to respond to potential exploitation attempts.

1. Restrict physical and local access to Huawei devices running affected HarmonyOS versions to trusted personnel only, minimizing the risk of local exploitation. 2. Implement strict endpoint security controls, including application whitelisting and behavior monitoring, to detect and prevent unauthorized local activities that could exploit the vulnerability. 3. Monitor Huawei's security advisories closely for patches or updates addressing CVE-2025-66329 and apply them promptly once available. 4. Employ network segmentation to isolate critical devices and limit lateral movement opportunities for attackers who gain local access. 5. Conduct regular security audits and penetration testing focusing on local privilege escalation and denial-of-service scenarios on HarmonyOS devices. 6. Educate users and administrators about the risks of local exploitation and enforce policies to prevent installation of untrusted software. 7. Consider deploying endpoint detection and response (EDR) solutions capable of identifying anomalous window management or system behavior indicative of exploitation attempts. 8. For organizations with high dependency on Huawei devices, evaluate alternative platforms or redundancy strategies to mitigate potential availability impacts.