CVE-2025-66334 is a vulnerability identified in Huawei's HarmonyOS, specifically within the office service component. The root cause is a CWE-494 weakness: downloading code without performing integrity checks. This deficiency allows an attacker to supply malicious or malformed code that, when processed by the office service, can cause a denial of service (DoS) condition, impacting system availability. The affected versions include HarmonyOS 5.0.1, 5.1.0, and 6.0.0. The vulnerability requires local access (attack vector: local) and user interaction, but no privileges or authentication are necessary, which somewhat limits the attack surface. The CVSS v3.1 score is 3.3, reflecting low severity primarily due to the limited impact scope (availability only) and exploitation complexity. No known exploits have been reported in the wild, and no official patches have been released at the time of publication. The vulnerability could be exploited by tricking a user into downloading malicious code through the office service, leading to service disruption. The lack of integrity checks means the system cannot verify the authenticity or correctness of the downloaded code, making it vulnerable to tampering or corruption. This flaw does not affect confidentiality or integrity of data but can degrade user experience and operational continuity by causing application or system crashes.

For European organizations, the primary impact is on availability of systems running Huawei HarmonyOS, particularly those utilizing the office service. Disruptions could affect productivity and business continuity, especially in environments where HarmonyOS devices are integrated into critical workflows. Although the vulnerability does not compromise data confidentiality or integrity, denial of service conditions can lead to downtime, loss of user trust, and potential operational delays. Organizations in sectors such as telecommunications, government, and enterprises with Huawei device deployments may face increased risk. The requirement for local access and user interaction reduces the likelihood of remote large-scale exploitation but insider threats or social engineering could still trigger the vulnerability. Given the growing adoption of Huawei technology in some European markets, the impact could be more pronounced in countries with higher market penetration. The absence of known exploits and patches currently limits immediate risk but also underscores the need for proactive monitoring and mitigation.

1. Restrict local access to devices running affected versions of HarmonyOS, ensuring only trusted users can interact with the office service. 2. Educate users to avoid downloading or opening untrusted files or code within the office service to reduce the risk of triggering the vulnerability. 3. Implement endpoint monitoring to detect abnormal crashes or service disruptions related to the office service. 4. Employ application whitelisting or integrity verification tools where possible to detect unauthorized code execution. 5. Maintain up-to-date backups and incident response plans to quickly recover from potential denial of service events. 6. Monitor Huawei security advisories for patches or updates addressing CVE-2025-66334 and apply them promptly once available. 7. Consider network segmentation to isolate HarmonyOS devices from critical infrastructure to limit potential impact. 8. Conduct regular security assessments focusing on local privilege escalation and social engineering vectors that could facilitate exploitation.