CVE-2025-62560 is a vulnerability classified under CWE-822 (Untrusted Pointer Dereference) found in Microsoft Office Online Server, specifically affecting the Excel component. The vulnerability arises when the software dereferences pointers that have not been properly validated or sanitized, leading to potential memory corruption. This flaw can be exploited by an unauthorized attacker who gains local access to the system and can trick a user into interacting with a maliciously crafted Excel file or component. Successful exploitation allows the attacker to execute arbitrary code with the privileges of the user running the Office Online Server process, potentially leading to full system compromise. The CVSS v3.1 score of 7.8 reflects a high severity, with attack vector local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), and requiring user interaction (UI:R). The impact on confidentiality, integrity, and availability is rated high, indicating that exploitation could lead to data disclosure, modification, or service disruption. Currently, no patches or known exploits are publicly available, but the vulnerability is reserved and published, signaling that Microsoft is aware and likely working on a fix. The vulnerability affects version 16.0.0.0 of Office Online Server, a widely used platform for hosting and rendering Office documents in enterprise environments.

For European organizations, the impact of CVE-2025-62560 could be substantial, especially for those relying on Microsoft Office Online Server to provide document collaboration and editing services. Exploitation could lead to unauthorized code execution on critical servers, risking data breaches, service outages, and potential lateral movement within networks. Confidential business information and personal data protected under GDPR could be exposed, leading to regulatory penalties and reputational damage. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, particularly in environments where endpoint security is weak or insider threats exist. Organizations in sectors such as finance, government, healthcare, and critical infrastructure, which heavily depend on Office Online Server, may face operational disruptions and increased incident response costs. The absence of known exploits currently provides a window for proactive defense, but the high severity score necessitates urgent attention.

1. Monitor Microsoft security advisories closely and apply patches immediately upon release to remediate the vulnerability. 2. Restrict local access to servers running Office Online Server to trusted administrators only, using strong authentication and access controls. 3. Implement application whitelisting and endpoint protection to detect and block unauthorized code execution attempts. 4. Educate users about the risks of interacting with untrusted or suspicious Office documents, emphasizing caution with Excel files. 5. Employ network segmentation to isolate Office Online Server infrastructure from less secure network zones. 6. Enable detailed logging and continuous monitoring to detect anomalous behavior indicative of exploitation attempts. 7. Conduct regular vulnerability assessments and penetration testing focusing on Office Online Server deployments. 8. Prepare incident response plans specifically addressing potential exploitation of this vulnerability to minimize impact.