CVE-2025-60727 is an out-of-bounds read vulnerability classified under CWE-125 affecting Microsoft Office Online Server, specifically its Excel processing component in version 16.0.0.0. This vulnerability arises from improper bounds checking during memory operations, allowing an attacker to read memory outside the intended buffer. Exploitation can lead to local code execution, enabling an attacker without privileges to run arbitrary code on the affected system. The attack vector is local (AV:L), requiring user interaction (UI:R) but no privileges (PR:N), and the scope is unchanged (S:U). The vulnerability impacts confidentiality, integrity, and availability at a high level (C:H/I:H/A:H), reflected in a CVSS 3.1 base score of 7.8. Although no public exploits are currently known, the vulnerability's nature suggests that attackers with local access could leverage crafted Excel files or interactions to trigger the flaw. The vulnerability was reserved on 2025-09-26 and published on 2025-11-11, with no patches currently listed, indicating a need for vigilance and prompt patch application once available. The vulnerability is significant because Office Online Server is widely used in enterprise environments for collaborative document editing and processing, making it a valuable target for attackers seeking local code execution capabilities.

For European organizations, this vulnerability poses a significant risk, particularly for enterprises and public sector entities relying on Microsoft Office Online Server for Excel document processing. Successful exploitation could lead to unauthorized code execution on servers, potentially allowing attackers to escalate privileges, move laterally within networks, or disrupt services. Confidential data processed or stored via Office Online Server could be exposed or manipulated, impacting data privacy and compliance with regulations such as GDPR. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, especially in environments with many users or where attackers have gained initial footholds. Critical infrastructure, financial institutions, and government agencies using Office Online Server are particularly vulnerable to operational disruption or data breaches. The lack of known exploits currently provides a window for proactive defense, but the high severity score underscores the urgency of mitigation.

1. Monitor Microsoft security advisories closely and apply official patches immediately upon release to address CVE-2025-60727. 2. Restrict local access to Office Online Server hosts to trusted administrators and users only, minimizing the attack surface. 3. Implement strict user privilege management to prevent unauthorized local access and reduce the risk of exploitation. 4. Employ application whitelisting and endpoint protection solutions to detect and block suspicious activities related to Office Online Server processes. 5. Conduct regular security audits and vulnerability assessments focusing on Office Online Server deployments. 6. Educate users about the risks of interacting with untrusted Excel files, especially in environments where Office Online Server is accessible. 7. Use network segmentation to isolate Office Online Server infrastructure from less secure network zones. 8. Enable detailed logging and monitoring of Office Online Server events to detect anomalous behavior indicative of exploitation attempts.