CVE-2025-62559 is a use-after-free vulnerability categorized 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 an object is improperly freed but later accessed, leading to undefined behavior that can be exploited for arbitrary code execution. An attacker can exploit this vulnerability by convincing a user to open or interact with a specially crafted Word document hosted or accessed via SharePoint. The attack requires no prior privileges (PR:N) but does require user interaction (UI:R), such as opening a malicious document. The vulnerability impacts confidentiality, integrity, and availability (all rated high), enabling an attacker to execute code with the privileges of the user, potentially leading to full system compromise. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) reflects that the attack is local, with low complexity and no privileges required, but user interaction is necessary. No patches or mitigations have been officially released as of the publication date (December 9, 2025), and no known exploits are currently active in the wild. This vulnerability is critical for organizations relying on SharePoint 2016 for document management and collaboration, as it could allow attackers to bypass security controls and execute malicious code within enterprise environments.

For European organizations, the impact of CVE-2025-62559 is significant due to the widespread use of Microsoft SharePoint Enterprise Server 2016 in enterprise and government sectors. Exploitation could lead to unauthorized code execution on affected systems, resulting in data breaches, disruption of business operations, and potential lateral movement within networks. Confidential information stored or processed via SharePoint could be compromised, impacting compliance with GDPR and other data protection regulations. The vulnerability could also be leveraged to deploy ransomware or other malware, affecting availability and causing financial and reputational damage. Organizations with remote or hybrid workforces are particularly at risk if users interact with malicious documents. The lack of an official patch increases the urgency for interim mitigations to reduce exposure. Critical infrastructure sectors such as finance, healthcare, and public administration in Europe could face elevated risks due to the strategic importance of SharePoint for collaboration and document workflows.

1. Immediately restrict or disable the handling of Word documents through SharePoint portals until a patch is available. 2. Implement strict email and document filtering to block or quarantine suspicious Word documents, especially those originating from untrusted sources. 3. Educate users about the risks of opening unsolicited or unexpected documents and enforce policies for verifying document authenticity. 4. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and prevent execution of unauthorized code. 5. Use sandboxing technologies to open documents in isolated environments, minimizing the risk of local code execution. 6. Monitor SharePoint and endpoint logs for unusual activity indicative of exploitation attempts. 7. Keep all related Microsoft products and operating systems up to date with the latest security patches and advisories. 8. Prepare incident response plans specifically addressing potential exploitation of this vulnerability. 9. Consider network segmentation to limit the spread of any compromise originating from SharePoint servers. 10. Stay informed about official patches or updates from Microsoft and apply them promptly once released.