CVE-2025-29793 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 deserializes data from untrusted sources without sufficient validation or sanitization, potentially allowing attackers to manipulate the deserialized objects to execute arbitrary code. In this case, the vulnerability allows an authorized attacker—meaning one with valid credentials—to execute code remotely over the network. The CVSS 3.1 base score of 7.2 reflects a high impact on confidentiality, integrity, and availability, with low attack complexity and no user interaction required. The vulnerability does not require user interaction but does require the attacker to have some level of privileges (PR:H), indicating that the attacker must be authenticated with elevated rights within the SharePoint environment. Exploitation could lead to full compromise of the SharePoint server, allowing attackers to execute arbitrary code, potentially leading to data theft, service disruption, or lateral movement within the network. No known public exploits are currently reported, and no patches have been linked yet, indicating that organizations should prioritize monitoring and mitigation efforts proactively. The vulnerability was published on April 8, 2025, with the reservation date on March 11, 2025, and has been enriched by CISA, highlighting its significance in the cybersecurity community.

For European organizations, the impact of this vulnerability could be substantial, especially for those relying heavily on Microsoft SharePoint Enterprise Server 2016 for document management, collaboration, and internal workflows. Successful exploitation could lead to unauthorized code execution on critical servers, resulting in data breaches involving sensitive corporate or personal data protected under GDPR. This could cause regulatory penalties, reputational damage, and operational disruptions. Additionally, attackers could leverage this vulnerability to establish persistent footholds or move laterally within networks, potentially compromising other critical infrastructure. Given the high confidentiality, integrity, and availability impacts, organizations could face downtime of collaboration services, loss or manipulation of critical documents, and exposure of intellectual property. The requirement for authenticated access somewhat limits exploitation to insiders or compromised accounts, but insider threats or credential theft remain realistic attack vectors. The lack of known exploits currently provides a window for mitigation before widespread attacks emerge, but the severity demands immediate attention.

European organizations should implement the following specific mitigations: 1) Immediately audit and restrict SharePoint user privileges to the minimum necessary, ensuring that only trusted users have elevated access that could exploit this vulnerability. 2) Monitor SharePoint logs and network traffic for unusual deserialization activity or anomalous behavior indicative of exploitation attempts. 3) Apply strict network segmentation and access controls to limit exposure of SharePoint servers to only trusted internal networks and VPNs. 4) Implement multi-factor authentication (MFA) for all SharePoint users to reduce the risk of credential compromise. 5) Regularly review and update incident response plans to include scenarios involving SharePoint compromise. 6) Stay alert for official patches or security updates from Microsoft and apply them promptly once available. 7) Consider deploying application-layer firewalls or runtime application self-protection (RASP) solutions that can detect and block malicious deserialization payloads. 8) Conduct internal penetration testing focused on deserialization vulnerabilities to identify potential exploitation paths. These steps go beyond generic advice by focusing on privilege management, monitoring, network controls, and proactive detection tailored to this specific vulnerability context.