CVE-2025-60726 is an out-of-bounds read vulnerability classified under CWE-125 found in Microsoft Office Online Server's Excel component, version 16.0.0.0. The vulnerability arises when the software improperly handles memory boundaries during Excel file processing, allowing an attacker to read memory locations beyond the intended buffer. This can lead to unauthorized disclosure of sensitive information stored in adjacent memory areas. The attack vector is local, meaning the attacker must have local access to the system but does not require any privileges (PR:N). However, user interaction is necessary (UI:R), such as opening a malicious Excel file through the Office Online Server interface. The vulnerability affects confidentiality (C:H) and availability (A:H) but not integrity (I:N). The CVSS 3.1 score of 7.1 indicates a high severity due to the potential for significant information leakage and possible application crashes or denial of service. No known exploits have been reported in the wild, and no official patches have been released as of the publication date. The vulnerability was reserved on 2025-09-26 and published on 2025-11-11. Given the widespread use of Microsoft Office Online Server in enterprise environments for collaborative document editing and processing, this vulnerability poses a notable risk, especially in environments where sensitive Excel data is handled. Attackers exploiting this flaw could gain access to confidential information without authentication, potentially leading to data breaches or disruption of services.

For European organizations, the impact of CVE-2025-60726 is significant due to the widespread deployment of Microsoft Office Online Server in corporate, governmental, and educational institutions. The vulnerability enables unauthorized local attackers to extract sensitive information from memory, potentially exposing confidential business data, personal information, or intellectual property. This could lead to compliance violations under GDPR and other data protection regulations, resulting in legal and financial penalties. Additionally, the vulnerability's ability to cause denial of service could disrupt critical business operations, impacting availability of document collaboration services. Organizations relying heavily on Excel for financial, operational, or strategic data processing are particularly vulnerable. The requirement for user interaction means phishing or social engineering could be used to trick users into opening malicious files, increasing the attack surface. The absence of a patch at the time of disclosure necessitates immediate risk management to prevent exploitation. Overall, the vulnerability threatens confidentiality and availability, with potential cascading effects on organizational trust and operational continuity.

1. Restrict local access to systems running Microsoft Office Online Server to trusted personnel only, minimizing the risk of unauthorized local exploitation. 2. Implement strict network segmentation and access controls to limit exposure of Office Online Server instances, especially those processing sensitive Excel documents. 3. Educate users about the risks of opening untrusted Excel files via Office Online Server interfaces to reduce the likelihood of successful user interaction exploitation. 4. Monitor system logs and network traffic for unusual activity indicative of exploitation attempts, such as abnormal memory access patterns or application crashes. 5. Prepare incident response plans specifically addressing potential information disclosure and denial of service scenarios related to this vulnerability. 6. Stay alert for official patches or security updates from Microsoft and prioritize their deployment immediately upon release. 7. Consider deploying application whitelisting or sandboxing techniques to isolate Office Online Server processes and limit the impact of potential exploitation. 8. Evaluate alternative document processing workflows that reduce reliance on vulnerable versions until patches are available. 9. Conduct regular vulnerability assessments and penetration testing focusing on Office Online Server environments to identify and remediate related weaknesses.