CVE-2025-59222 is a use-after-free vulnerability classified under CWE-416, affecting Microsoft SharePoint Enterprise Server 2016 (version 16.0.0). The flaw resides in the way Microsoft Office Word components handle memory, leading to a use-after-free condition that can be triggered when a user opens or interacts with a specially crafted document. This vulnerability allows an attacker without privileges to execute arbitrary code locally on the affected system, potentially leading to full compromise of the SharePoint server or client machines depending on deployment. The CVSS 3.1 base score of 7.8 reflects high impact on confidentiality, integrity, and availability, with an attack vector requiring local access (AV:L), low attack complexity (AC:L), no privileges (PR:N), but user interaction (UI:R). The scope remains unchanged (S:U), meaning the vulnerability affects only the vulnerable component. No known exploits have been reported in the wild, and no official patches have been released as of the publication date (October 14, 2025). The vulnerability's exploitation could allow attackers to execute arbitrary code, potentially leading to data theft, service disruption, or further lateral movement within an enterprise network. Given SharePoint's widespread use in enterprise collaboration and document management, this vulnerability poses a significant risk to organizations relying on SharePoint 2016.

For European organizations, the impact of CVE-2025-59222 could be substantial. SharePoint Enterprise Server 2016 is widely used across various sectors including government, finance, healthcare, and manufacturing, all of which handle sensitive data and require high availability. Successful exploitation could lead to unauthorized code execution, resulting in data breaches, intellectual property theft, disruption of business operations, and potential compliance violations under GDPR. The local attack vector and requirement for user interaction mean that insider threats or targeted phishing campaigns could be effective attack vectors. Additionally, compromised SharePoint servers could serve as pivot points for attackers to infiltrate broader enterprise networks. The lack of an available patch increases the urgency for organizations to implement interim mitigations to protect their environments.

1. Restrict and monitor the handling of Microsoft Word documents within SharePoint environments, especially those originating from untrusted sources. 2. Implement strict user training and awareness programs to reduce the risk of users opening malicious documents. 3. Employ application whitelisting and endpoint protection solutions capable of detecting anomalous behavior related to use-after-free exploitation. 4. Use network segmentation to limit the exposure of SharePoint servers and restrict lateral movement in case of compromise. 5. Regularly audit and monitor SharePoint logs and system behavior for signs of exploitation attempts or unusual activity. 6. Apply the principle of least privilege to SharePoint users and service accounts to minimize potential damage. 7. Stay informed about official Microsoft security advisories and apply patches immediately once available. 8. Consider deploying virtual patching or intrusion prevention systems that can detect and block exploitation attempts targeting this vulnerability.