CVE-2025-26630 is a use-after-free vulnerability classified under CWE-416, found in Microsoft Office Access, part of Microsoft 365 Apps for Enterprise version 16.0.1. The vulnerability arises from improper handling of memory objects that have been freed, allowing an attacker to execute arbitrary code locally. Specifically, when a user opens a specially crafted file or interacts with malicious content within Office Access, the application may attempt to use memory that has already been released, leading to memory corruption. This corruption can be leveraged to execute code with the privileges of the current user. The attack vector requires local access and user interaction but does not require any prior authentication or elevated privileges, making it accessible to a wide range of threat actors. The CVSS v3.1 score of 7.8 reflects high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Although no public exploits are known at this time, the vulnerability's nature and the ubiquity of Microsoft 365 Apps make it a significant risk. The vulnerability was reserved in February 2025 and published in March 2025, with no patch links currently available, indicating that remediation is pending or in progress. Organizations using the affected version should prepare for immediate patch deployment once available and consider interim mitigations.

The vulnerability allows unauthorized local attackers to execute arbitrary code with the privileges of the logged-in user, potentially leading to full compromise of the affected system. For European organizations, this could result in data breaches, disruption of business operations, and compromise of sensitive information handled within Microsoft Office Access databases. Given the integration of Microsoft 365 Apps in many enterprise environments, exploitation could facilitate lateral movement within networks, data exfiltration, or deployment of ransomware. The impact is particularly critical for sectors handling sensitive or regulated data, such as finance, healthcare, and government. The requirement for user interaction somewhat limits remote exploitation but does not eliminate risk, especially in environments where users frequently open Office documents from external sources. The absence of known exploits currently reduces immediate risk but also means organizations must act proactively. The vulnerability affects confidentiality, integrity, and availability, making it a comprehensive threat to organizational security.

1. Monitor Microsoft security advisories closely and apply official patches immediately upon release to remediate the vulnerability. 2. Until patches are available, restrict usage of Microsoft Office Access version 16.0.1 by limiting access to trusted users and environments. 3. Implement application whitelisting and endpoint protection solutions that can detect and block exploitation attempts targeting use-after-free conditions. 4. Educate users about the risks of opening unsolicited or suspicious Office documents, emphasizing cautious handling of email attachments and downloads. 5. Employ network segmentation to limit the impact of potential local compromises and prevent lateral movement. 6. Use Microsoft Defender for Endpoint or similar tools to monitor for anomalous behaviors indicative of exploitation attempts. 7. Regularly back up critical data and verify restoration procedures to mitigate potential data loss from exploitation. 8. Consider disabling or restricting macros and ActiveX controls in Office documents where feasible to reduce attack surface.