CVE-2025-62200 is a vulnerability classified under CWE-822 (Untrusted Pointer Dereference) affecting Microsoft Office Online Server, specifically version 16.0.0.0. The vulnerability arises from improper handling of pointers within Microsoft Office Excel components in the Office Online Server environment. An attacker who can trick a user into interacting with a maliciously crafted Excel file or component can cause the server process to dereference untrusted pointers, leading to arbitrary code execution locally. The vulnerability does not require prior authentication (PR:N) but does require user interaction (UI:R), such as opening or processing a malicious file. The attack vector is local (AV:L), meaning the attacker must have local access to the system or be able to execute code locally to trigger the flaw. The vulnerability impacts confidentiality, integrity, and availability at a high level (C:H/I:H/A:H), potentially allowing full system compromise. The CVSS score of 7.8 reflects the high impact and moderate complexity of exploitation. No public exploits are currently known, and no patches have been linked yet, indicating that organizations should monitor for updates from Microsoft. The vulnerability is particularly concerning in environments where Office Online Server is exposed to multiple users or integrated into collaborative workflows, as it could facilitate lateral movement or privilege escalation within internal networks.

For European organizations, the impact of CVE-2025-62200 can be significant, especially for enterprises and public sector entities relying on Microsoft Office Online Server for document collaboration and productivity. Successful exploitation could lead to local code execution on critical servers, resulting in data breaches, disruption of business operations, and potential spread of malware within internal networks. Confidential information processed or stored via Office Online Server could be exposed or altered, undermining data integrity and compliance with regulations such as GDPR. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, particularly in environments with shared or poorly segmented access. Organizations in sectors like finance, government, healthcare, and critical infrastructure in Europe could face operational and reputational damage if this vulnerability is exploited. Additionally, the lack of known exploits currently provides a window for proactive mitigation before active attacks emerge.

1. Monitor Microsoft security advisories closely and apply official patches or updates for Office Online Server as soon as they become available. 2. Restrict local access to Office Online Server hosts to trusted administrators only, minimizing the risk of local exploitation. 3. Implement strict user privilege management and enforce the principle of least privilege to reduce the impact of potential local code execution. 4. Employ application whitelisting and endpoint protection solutions on servers hosting Office Online Server to detect and block suspicious activities. 5. Use network segmentation to isolate Office Online Server infrastructure from less trusted network zones and limit lateral movement opportunities. 6. Educate users and administrators about the risks of opening untrusted or unexpected Excel files, especially in environments where Office Online Server is accessible. 7. Enable detailed logging and monitoring on Office Online Server to detect anomalous behavior indicative of exploitation attempts. 8. Consider deploying additional security controls such as Host Intrusion Prevention Systems (HIPS) and Endpoint Detection and Response (EDR) tools to identify and respond to exploitation attempts rapidly.