CVE-2025-30382 is a high-severity vulnerability classified under CWE-502, which involves the deserialization of untrusted data in Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). Deserialization vulnerabilities occur when an application processes serialized data from untrusted sources without proper validation or sanitization, allowing attackers to manipulate the serialized objects. In this specific case, an unauthorized attacker can exploit the flaw by providing crafted serialized data to the SharePoint server, leading to the execution of arbitrary code locally on the affected system. The vulnerability requires local access vector (AV:L), meaning the attacker must have some level of access to the system or network where SharePoint is running. No privileges are required (PR:N), but user interaction is necessary (UI:R), indicating that the exploit might involve tricking a user into performing an action such as opening a malicious file or link. The vulnerability impacts confidentiality, integrity, and availability (all rated high), suggesting that successful exploitation could lead to full system compromise, data theft, or service disruption. The CVSS 3.1 base score is 7.8, reflecting the significant risk posed by this vulnerability. Although no known exploits are currently reported in the wild, the presence of this flaw in a widely used enterprise collaboration platform like SharePoint makes it a critical concern for organizations relying on this software for document management and internal communications. The absence of published patches at the time of disclosure further increases the urgency for mitigation and monitoring.

For European organizations, the impact of CVE-2025-30382 can be substantial. Microsoft SharePoint Enterprise Server 2016 is commonly used across various sectors including government, finance, healthcare, and large enterprises for collaboration and document management. Exploitation of this vulnerability could allow attackers to execute arbitrary code on SharePoint servers, potentially leading to unauthorized access to sensitive documents, intellectual property theft, and disruption of business operations. Given the high confidentiality and integrity impact, attackers could manipulate or exfiltrate critical data, violating GDPR and other data protection regulations, which could result in severe legal and financial penalties. The requirement for user interaction means phishing or social engineering campaigns could be leveraged to trigger the exploit, increasing the attack surface. Additionally, availability impacts could disrupt internal workflows and collaboration, causing operational downtime. The lack of known exploits currently provides a window for proactive defense, but the vulnerability’s nature suggests it could be targeted by advanced persistent threat (APT) groups or cybercriminals aiming at high-value European targets.

To mitigate CVE-2025-30382 effectively, European organizations should implement a multi-layered approach beyond generic patching advice. First, apply any available security updates or patches from Microsoft immediately once released. Until patches are available, restrict access to SharePoint servers by enforcing strict network segmentation and limiting local access to trusted administrators only. Employ application whitelisting and endpoint protection solutions capable of detecting anomalous deserialization behaviors or suspicious code execution patterns. Conduct targeted user awareness training focusing on phishing and social engineering risks, as user interaction is required for exploitation. Implement robust monitoring and logging on SharePoint servers to detect unusual activities, such as unexpected deserialization calls or privilege escalations. Consider deploying Web Application Firewalls (WAF) with custom rules to detect and block malicious serialized payloads. Regularly review and harden SharePoint configurations, disabling unnecessary features that might increase the attack surface. Finally, perform penetration testing and vulnerability assessments specifically targeting deserialization vectors to identify and remediate weaknesses proactively.