CVE-2025-24082 is a use-after-free vulnerability categorized under CWE-416 found in Microsoft Office Online Server, specifically impacting the Excel component. This vulnerability arises when the software improperly manages memory, freeing an object while it is still in use, which can lead to memory corruption. An attacker exploiting this flaw can execute arbitrary code locally on the affected system. The vulnerability affects version 1.0.0 of Office Online Server and was published on March 11, 2025. The CVSS v3.1 base score is 7.8, indicating a high severity level. The attack vector is local (AV:L), requiring low attack complexity (AC:L), no privileges (PR:N), but user interaction (UI:R). The scope is unchanged (S:U), and the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits are currently reported in the wild, but the vulnerability is considered critical due to the potential for code execution. The vulnerability could be triggered when a user opens or interacts with a malicious Excel file hosted or processed via Office Online Server, leading to local code execution and potential system compromise. The lack of available patches at the time of reporting increases the urgency for mitigation through other controls.

For European organizations, the impact of CVE-2025-24082 could be significant, especially for enterprises and public sector entities relying on Microsoft Office Online Server for collaborative document editing and processing. Successful exploitation could lead to unauthorized code execution, resulting in data breaches, loss of data integrity, and disruption of service availability. This could affect sensitive business information, intellectual property, and critical operational data. The local attack vector means that attackers would need some form of access or trick users into interacting with malicious content, which could be achieved via phishing or insider threats. Given the high confidentiality, integrity, and availability impacts, exploitation could lead to severe operational disruptions and reputational damage. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and regulatory requirements under GDPR and other European data protection laws.

1. Apply official patches from Microsoft immediately once they become available to remediate the vulnerability in Office Online Server version 1.0.0. 2. Until patches are released, restrict local access to systems running Office Online Server to trusted personnel only. 3. Implement strict user access controls and least privilege principles to minimize the risk of unauthorized local code execution. 4. Educate users about the risks of interacting with untrusted Excel files, especially those received via email or external sources. 5. Monitor logs and endpoint detection systems for unusual behavior indicative of exploitation attempts, such as unexpected process creation or memory corruption indicators. 6. Employ application whitelisting and endpoint protection solutions that can detect or block exploitation techniques related to use-after-free vulnerabilities. 7. Consider network segmentation to isolate Office Online Server environments from broader enterprise networks to limit lateral movement in case of compromise. 8. Regularly review and update incident response plans to include scenarios involving local code execution vulnerabilities in collaboration platforms.