CVE-2025-26629 is a use-after-free vulnerability classified under CWE-416 affecting Microsoft 365 Apps for Enterprise, specifically version 16.0.1. Use-after-free vulnerabilities occur when a program continues to use a pointer after the memory it points to has been freed, leading to undefined behavior including potential arbitrary code execution. In this case, the vulnerability allows an unauthorized attacker to execute code locally on the victim's machine. The attack vector is local with low attack complexity, requiring no privileges but some user interaction, such as opening a crafted malicious Office document. The vulnerability impacts confidentiality, integrity, and availability, as successful exploitation can lead to full system compromise. The CVSS v3.1 score of 7.8 reflects these factors, with a vector string indicating local attack vector (AV:L), low complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). There are currently no known exploits in the wild, but the vulnerability is publicly disclosed and patched status is pending or not linked yet. The vulnerability was reserved in February 2025 and published in March 2025. Given Microsoft 365 Apps for Enterprise's widespread use in enterprise environments, this vulnerability poses a significant risk if exploited. The lack of known exploits provides a window for mitigation before active attacks emerge.

For European organizations, the impact of CVE-2025-26629 is substantial due to the widespread adoption of Microsoft 365 Apps for Enterprise across public and private sectors. Exploitation could lead to local code execution, enabling attackers to escalate privileges, deploy malware, exfiltrate sensitive data, or disrupt operations. This is particularly critical for sectors handling sensitive personal data under GDPR, financial institutions, government agencies, and critical infrastructure operators. The vulnerability's requirement for user interaction means phishing or social engineering campaigns could be effective attack vectors. The potential for full system compromise threatens confidentiality, integrity, and availability of organizational assets, potentially leading to data breaches, operational downtime, and reputational damage. The absence of known exploits currently reduces immediate risk but also means organizations must act proactively. The impact is amplified in environments where endpoint security controls are weak or patch management is delayed.

1. Monitor Microsoft security advisories closely and apply patches for Microsoft 365 Apps for Enterprise version 16.0.1 as soon as they are released. 2. Implement strict email and document filtering to block or quarantine suspicious Office documents, especially from untrusted sources. 3. Educate users on the risks of opening unsolicited or unexpected Office documents and encourage verification of document sources. 4. Employ application control or whitelisting solutions to restrict execution of unauthorized code on endpoints. 5. Utilize endpoint detection and response (EDR) tools to monitor for anomalous behaviors indicative of exploitation attempts. 6. Enforce least privilege principles to limit the impact of local code execution. 7. Regularly audit and update endpoint security configurations to ensure defenses against use-after-free exploitation techniques. 8. Consider disabling or restricting macros and embedded content in Office documents where feasible. 9. Maintain robust backup and recovery procedures to mitigate potential ransomware or destructive payloads delivered via this vulnerability.