CVE-2025-30384 is a high-severity vulnerability affecting Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). The vulnerability is classified under CWE-502, which involves the deserialization of untrusted data. Deserialization vulnerabilities occur when an application processes serialized data from untrusted sources without proper validation or sanitization, allowing attackers to manipulate the data to execute arbitrary code. In this case, an unauthorized attacker can exploit this flaw to execute code locally on the SharePoint server. The CVSS 3.1 base score is 7.4, indicating a high impact with the vector AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H, meaning the attack requires local access with high attack complexity, no privileges, and no user interaction, but can fully compromise confidentiality, integrity, and availability. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk due to the critical role SharePoint plays in enterprise collaboration and document management. The lack of available patches at the time of publication increases the urgency for organizations to implement mitigations. The vulnerability allows code execution locally, which could be leveraged by attackers who have gained limited access to escalate privileges or move laterally within a network. Given SharePoint's integration with other Microsoft services and its widespread use in enterprise environments, this vulnerability could be a vector for broader compromise if exploited.

For European organizations, the impact of CVE-2025-30384 could be substantial. SharePoint Enterprise Server 2016 is widely used across various sectors including government, finance, healthcare, and large enterprises for document management and collaboration. Successful exploitation could lead to unauthorized code execution on critical servers, resulting in data breaches, disruption of business operations, and potential exposure of sensitive information protected under regulations such as GDPR. The high impact on confidentiality, integrity, and availability means attackers could steal or alter sensitive data, deploy ransomware, or disrupt services. Given the local access requirement, the threat is particularly relevant in scenarios where attackers have already gained foothold inside the network, such as through phishing or insider threats. The absence of known exploits currently provides a window for proactive defense, but organizations should not underestimate the risk given the potential for rapid weaponization once exploit code becomes available.

Beyond applying patches when they become available, European organizations should implement several specific mitigations: 1) Restrict and monitor local access to SharePoint servers, ensuring only trusted administrators have access. 2) Employ network segmentation to isolate SharePoint servers from less trusted network zones, limiting lateral movement opportunities. 3) Use application whitelisting and endpoint protection to detect and prevent unauthorized code execution on SharePoint servers. 4) Enable detailed logging and continuous monitoring of SharePoint server activities to detect anomalous behavior indicative of exploitation attempts. 5) Conduct regular security audits and vulnerability assessments focused on deserialization risks and input validation in custom SharePoint extensions or integrations. 6) Educate IT staff about the risks of deserialization vulnerabilities and the importance of applying security updates promptly. 7) Implement strict access controls and multi-factor authentication for administrative accounts to reduce the risk of unauthorized local access. These measures, combined with timely patching, will reduce the attack surface and improve detection and response capabilities.