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 the Microsoft Office Excel component, which is part of the Office Online Server suite. An attacker who can induce the vulnerable code path can cause the server to dereference untrusted pointers, leading to arbitrary code execution locally on the affected machine. The vulnerability does not require any privileges (PR:N) but does require user interaction (UI:R), such as opening a malicious Excel file or triggering a specific action within the Office Online Server environment. The CVSS v3.1 base score is 7.8, indicating a high severity level, with impacts rated high on confidentiality, integrity, and availability. The attack vector is local (AV:L), meaning the attacker must have local access to the system, which limits remote exploitation but does not eliminate risk, especially in environments where multiple users have access or where attackers can gain local footholds through other means. No known exploits are currently reported in the wild, but the vulnerability is publicly disclosed and should be considered a significant risk. The lack of available patches at the time of disclosure increases the urgency for organizations to implement interim mitigations and monitor for suspicious activity. The vulnerability could allow attackers to execute arbitrary code, potentially leading to full system compromise, data theft, or disruption of services hosted on Office Online Server.

For European organizations, the impact of CVE-2025-62200 can be substantial, especially for enterprises and public sector entities relying on Microsoft Office Online Server for document collaboration and productivity. Successful exploitation could lead to unauthorized code execution, enabling attackers to steal sensitive data, manipulate documents, or disrupt business operations. This is particularly critical for sectors such as finance, government, healthcare, and critical infrastructure, where confidentiality and integrity of documents are paramount. The local attack vector reduces the likelihood of widespread remote exploitation but increases risk in environments with shared access or insufficient endpoint security. Additionally, the high impact on availability could cause service outages, affecting business continuity. The absence of known exploits currently provides a window for proactive defense, but organizations must act swiftly to prevent potential future attacks. The vulnerability also raises concerns about insider threats or attackers leveraging initial access to escalate privileges and move laterally within networks.

Given the absence of an official patch at the time of disclosure, European organizations should implement several specific mitigations: 1) Restrict local access to Office Online Server hosts to trusted personnel only and enforce strict access controls and monitoring. 2) Employ application whitelisting and endpoint protection solutions to detect and block suspicious code execution attempts. 3) Monitor logs and system behavior for anomalies indicative of exploitation attempts, such as unusual pointer dereferences or process crashes related to Excel components. 4) Educate users about the risks of opening untrusted Excel files or interacting with suspicious content within Office Online Server environments. 5) Segment networks to limit lateral movement opportunities if an attacker gains local access. 6) Prepare for rapid deployment of patches once Microsoft releases them by maintaining an up-to-date inventory of affected systems. 7) Consider deploying virtual desktop infrastructure (VDI) or sandboxing techniques to isolate Office Online Server usage and reduce exposure. 8) Regularly review and update incident response plans to include scenarios involving local code execution vulnerabilities in critical collaboration platforms.