CVE-2025-49712 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 processed by an application’s deserialization mechanism, potentially allowing attackers to craft malicious payloads that execute arbitrary code during the deserialization process. In this case, an authorized attacker with network access to the SharePoint server can exploit this flaw to execute code remotely without requiring user interaction, leveraging the improper validation of serialized input data. The vulnerability has a CVSS v3.1 base score of 8.8, reflecting its high impact on confidentiality, integrity, and availability, combined with low attack complexity and no user interaction needed. The attacker must have some level of privileges (PR:L) but can execute code remotely (AV:N), which could lead to full system compromise, data theft, or disruption of SharePoint services. Although no public exploits are known yet, the vulnerability is critical due to the widespread use of SharePoint in enterprise environments and the potential for lateral movement within networks. The lack of an official patch at the time of disclosure necessitates immediate risk mitigation and monitoring by affected organizations.

For European organizations, the impact of CVE-2025-49712 can be severe. SharePoint is widely used across Europe for document management, collaboration, and intranet portals, often containing sensitive corporate and personal data. Successful exploitation could lead to unauthorized access to confidential information, modification or deletion of critical documents, and disruption of business operations. The ability to execute arbitrary code remotely may allow attackers to deploy ransomware, establish persistent backdoors, or move laterally within corporate networks, escalating the threat to broader IT infrastructure. Organizations in sectors such as finance, government, healthcare, and critical infrastructure are particularly vulnerable due to the sensitive nature of their data and regulatory compliance requirements under GDPR. The compromise of SharePoint servers could also damage organizational reputation and result in legal and financial penalties.

1. Immediately restrict network access to SharePoint Enterprise Server 2016 instances, limiting connections to trusted administrators and essential services only. 2. Enforce the principle of least privilege by reviewing and minimizing user permissions, especially those with administrative rights on SharePoint. 3. Implement network segmentation to isolate SharePoint servers from other critical systems and sensitive data repositories. 4. Enable detailed logging and monitoring of SharePoint deserialization processes and anomalous activities to detect potential exploitation attempts early. 5. Apply any available security updates or patches from Microsoft as soon as they are released; monitor Microsoft security advisories closely. 6. Consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious serialized payloads targeting SharePoint. 7. Conduct regular security assessments and penetration testing focused on SharePoint environments to identify and remediate weaknesses. 8. Educate IT and security teams about the risks of deserialization vulnerabilities and the importance of secure coding and configuration practices.