CVE-2025-59237 is a deserialization vulnerability classified under CWE-502 affecting Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). Deserialization vulnerabilities occur when untrusted data is deserialized by an application, potentially allowing attackers to manipulate the process to execute arbitrary code. In this case, the vulnerability allows an attacker with authorized access—meaning they must have some level of legitimate credentials—to send specially crafted data over the network to the SharePoint server. Because SharePoint often handles sensitive organizational data and integrates deeply with enterprise workflows, successful exploitation can lead to full compromise of the server. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) indicates that the attack can be performed remotely over the network with low attack complexity, requires low privileges but no user interaction, and impacts confidentiality, integrity, and availability at a high level. Although no public exploits are currently known, the vulnerability is critical due to the potential for remote code execution and the widespread use of SharePoint in enterprises. The lack of available patches at the time of publication increases the urgency for mitigation through access controls and monitoring. This vulnerability highlights the risks associated with deserialization of untrusted data, a common vector for remote code execution in complex enterprise software.

For European organizations, the impact of CVE-2025-59237 can be severe. SharePoint is widely used across government, financial, healthcare, and industrial sectors in Europe for document management and collaboration. Exploitation could lead to unauthorized data disclosure, modification, or deletion, disrupting critical business processes and potentially causing regulatory compliance violations under GDPR due to data breaches. The ability to execute arbitrary code remotely could allow attackers to establish persistent footholds, move laterally within networks, and escalate privileges, leading to broader compromise of enterprise IT environments. Availability impacts could result in downtime of collaboration services, affecting productivity and operational continuity. Given the high CVSS score and the critical role of SharePoint, organizations face significant risk if this vulnerability is not addressed promptly. The absence of known public exploits currently provides a window for proactive defense but also means attackers may develop exploits rapidly once the vulnerability becomes widely known.

1. Apply official Microsoft patches immediately once released for SharePoint Enterprise Server 2016 to remediate the vulnerability. 2. Until patches are available, restrict network access to SharePoint servers to only trusted internal IPs and VPN users. 3. Enforce the principle of least privilege by reviewing and limiting SharePoint user permissions, especially those with elevated rights. 4. Implement network segmentation to isolate SharePoint servers from other critical infrastructure. 5. Enable and monitor detailed logging on SharePoint servers to detect anomalous deserialization activities or unusual remote requests. 6. Use Web Application Firewalls (WAF) with custom rules to detect and block suspicious payloads targeting deserialization endpoints. 7. Conduct regular security assessments and penetration tests focusing on deserialization and input validation weaknesses. 8. Educate administrators and users about the risks of deserialization vulnerabilities and the importance of credential security to prevent unauthorized access. 9. Consider deploying endpoint detection and response (EDR) solutions to identify exploitation attempts and respond rapidly. 10. Maintain an incident response plan tailored to SharePoint compromise scenarios to minimize damage if exploitation occurs.