CVE-2025-62202 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. This vulnerability occurs when the software improperly handles memory boundaries during Excel file processing, allowing an attacker to read memory locations beyond the intended buffer. The flaw can be triggered by an unauthorized attacker with local access who convinces a user to interact with a crafted Excel file or component, leading to disclosure of sensitive information from memory. The vulnerability does not require privileges (PR:N) but does require user interaction (UI:R), and it affects confidentiality (C:H) and availability (A:H) without impacting integrity. The attack vector is local (AV:L), meaning the attacker must have access to the system hosting Office Online Server. The vulnerability is rated high severity with a CVSS 3.1 score of 7.1, reflecting its potential to expose sensitive data and disrupt service. No patches are currently available, and no known exploits have been reported in the wild. The vulnerability's impact is significant in environments where Office Online Server is used to process Excel files, especially in multi-user or cloud-hosted scenarios where local access might be possible through compromised accounts or insider threats.

For European organizations, this vulnerability poses a risk of sensitive data leakage and potential service disruption in environments using Microsoft Office Online Server, particularly the Excel component. Confidentiality is at risk due to unauthorized memory disclosure, which could expose sensitive business or personal data. Availability impact could disrupt business operations relying on Excel file processing. Sectors such as finance, government, healthcare, and critical infrastructure that use Office Online Server extensively are particularly vulnerable. The local attack vector means that insider threats or attackers who gain local access through other means could exploit this vulnerability. Given the widespread use of Microsoft products across Europe, the vulnerability could have broad implications if exploited, potentially leading to data breaches or operational downtime. The absence of known exploits currently reduces immediate risk but does not eliminate the potential for future attacks once exploit code becomes available.

Organizations should implement the following specific mitigations: 1) Monitor for updates from Microsoft and apply patches promptly once released to address CVE-2025-62202. 2) Restrict local access to servers running Office Online Server by enforcing strict access controls and limiting user permissions to only those necessary. 3) Employ application whitelisting and endpoint protection to detect and prevent execution of unauthorized or suspicious files that could trigger the vulnerability. 4) Conduct regular security audits and monitoring of Office Online Server logs to detect unusual activity indicative of exploitation attempts. 5) Educate users about the risks of interacting with untrusted Excel files, especially in environments where local access is possible. 6) Consider network segmentation to isolate Office Online Server hosts from less trusted networks or users. 7) Use virtualization or containerization to limit the impact of potential exploitation by isolating the Office Online Server environment. These steps go beyond generic advice by focusing on access control, monitoring, and user education tailored to the local attack vector and the nature of the vulnerability.