CVE-2025-59222 is a use-after-free vulnerability classified under CWE-416 affecting Microsoft SharePoint Enterprise Server 2016, specifically version 16.0.0. The flaw resides in the way Microsoft Office Word components handle memory, where a previously freed memory object is accessed, leading to undefined behavior. This memory corruption can be exploited by an attacker to execute arbitrary code locally on the victim's machine. The attack vector requires the victim to open or interact with a maliciously crafted Word document, which triggers the vulnerability. No privileges or prior authentication are required, but user interaction is necessary. The CVSS v3.1 base score is 7.8, indicating a high severity level, with impact on confidentiality, integrity, and availability rated as high. The vulnerability is currently published but lacks an official patch or known exploits in the wild. The exploitation could allow attackers to run code with the same privileges as the user, potentially leading to full system compromise. Given SharePoint's role in enterprise collaboration and document management, this vulnerability poses a significant risk to organizations relying on this platform, especially if users frequently handle Word documents within SharePoint environments.

For European organizations, the impact of CVE-2025-59222 could be substantial. SharePoint Enterprise Server 2016 is widely used in enterprises for document management and collaboration, often integrated with Microsoft Office products. Successful exploitation could lead to unauthorized code execution on user machines, enabling attackers to steal sensitive data, disrupt business operations, or move laterally within networks. Confidentiality breaches could expose intellectual property or personal data protected under GDPR, leading to regulatory penalties and reputational damage. Integrity and availability impacts could disrupt critical workflows and document access, affecting productivity. The requirement for user interaction limits remote exploitation but does not eliminate risk, especially in environments with frequent document sharing. The absence of a patch increases exposure time, necessitating immediate mitigations. Organizations with large numbers of SharePoint users or those in regulated sectors such as finance, healthcare, and government are particularly vulnerable.

Until an official patch is released, European organizations should implement several targeted mitigations. First, restrict or monitor the use of Word documents within SharePoint environments, especially those originating from untrusted sources. Employ application whitelisting and endpoint protection solutions capable of detecting anomalous behavior related to document processing. Enforce strict user training and awareness programs to reduce the likelihood of users opening suspicious documents. Utilize Microsoft Office Protected View and disable macros or other active content in documents by default. Network segmentation can limit lateral movement if exploitation occurs. Regularly audit SharePoint and Office installations to ensure they are updated with all other security patches. Implement enhanced logging and monitoring to detect potential exploitation attempts. Finally, prepare for rapid deployment of the official patch once available by maintaining an up-to-date asset inventory and patch management process.