CVE-2025-59240 is a vulnerability classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) affecting Microsoft Office LTSC 2021, specifically the Excel component version 16.0.1. The vulnerability allows an attacker with local access to the affected system to disclose sensitive information without requiring any privileges (PR:N) but does require user interaction (UI:R), such as opening a malicious Excel file or triggering a specific action within Excel. The attack vector is local (AV:L), meaning remote exploitation is not possible. The vulnerability impacts confidentiality (C:H) but does not affect integrity or availability. The scope is unchanged (S:U), indicating the vulnerability affects only the vulnerable component without impacting other system components. The vulnerability was published on November 11, 2025, and no known exploits are currently reported in the wild. The lack of a patch link suggests that a fix may be pending or in development. This vulnerability could allow attackers to access sensitive data stored or processed within Excel files or the application environment, potentially leading to data leakage or privacy violations. The medium CVSS score of 5.5 reflects moderate risk due to local access requirements and user interaction, but the high confidentiality impact elevates its importance in environments where sensitive data is handled.

For European organizations, this vulnerability poses a risk primarily to confidentiality of sensitive data processed or stored in Microsoft Excel within Office LTSC 2021 environments. Organizations that rely heavily on Excel for financial, personal, or proprietary data could face data leakage if an attacker gains local access and tricks a user into interaction. Sectors such as finance, healthcare, government, and critical infrastructure in Europe are particularly sensitive to such exposures. The local access requirement limits the attack surface but insider threats or compromised endpoints could be exploited. The absence of integrity or availability impact reduces the risk of operational disruption but does not diminish the potential regulatory and reputational damage from data exposure. Compliance with GDPR and other data protection regulations in Europe means that even local data leaks can have significant legal and financial consequences. Organizations with large deployments of Microsoft Office LTSC 2021 version 16.0.1, especially in countries with high Microsoft software adoption, are at greater risk.

1. Monitor Microsoft security advisories closely and apply patches or updates as soon as they become available to remediate the vulnerability. 2. Restrict local access to systems running Microsoft Office LTSC 2021 to trusted users only, employing strict access controls and endpoint security measures. 3. Educate users about the risks of interacting with untrusted Excel files or macros, emphasizing caution with files from unknown or suspicious sources. 4. Implement application whitelisting or sandboxing to limit the execution of potentially malicious Excel content. 5. Use data loss prevention (DLP) tools to monitor and control sensitive data exposure within Office applications. 6. Regularly audit and monitor local system activity for signs of unauthorized access or suspicious user interactions. 7. Consider deploying endpoint detection and response (EDR) solutions to detect exploitation attempts or anomalous behavior related to Excel processes. 8. Maintain up-to-date backups of critical data to mitigate potential secondary impacts from exploitation attempts.