CVE-2025-59226 is a use-after-free vulnerability classified under CWE-416 affecting Microsoft Office Visio within Microsoft 365 Apps for Enterprise version 16.0.1. This vulnerability arises from improper memory management where the application accesses memory after it has been freed, leading to undefined behavior that an attacker can exploit to execute arbitrary code locally. The attack vector requires local access and user interaction, such as opening a specially crafted Visio file, but does not require any privileges or authentication, increasing its risk profile. The vulnerability impacts confidentiality, integrity, and availability, as arbitrary code execution can lead to data theft, system manipulation, or denial of service. The CVSS v3.1 score of 7.8 reflects high severity with low attack complexity and no privileges required, but user interaction is necessary. No public exploits or patches are currently available, but the vulnerability is publicly disclosed and should be considered a priority for mitigation. The vulnerability affects a widely used enterprise productivity suite, increasing the potential attack surface in corporate environments. Given the integration of Visio in many business processes, exploitation could disrupt workflows and compromise sensitive information.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Microsoft 365 Apps for Enterprise, including Visio, in business, government, and critical infrastructure sectors. Successful exploitation could lead to local code execution, enabling attackers to install malware, exfiltrate data, or disrupt operations. The impact on confidentiality is high as sensitive corporate and personal data could be accessed or modified. Integrity and availability are also at risk, as attackers could alter files or cause application crashes, potentially leading to denial of service. The requirement for user interaction means phishing or social engineering campaigns could be used to deliver malicious Visio files. Given the high adoption of Microsoft 365 in Europe, especially in countries with strong digital economies and critical infrastructure, the threat could affect a broad range of sectors including finance, healthcare, manufacturing, and government agencies. The lack of known exploits in the wild currently reduces immediate risk, but the public disclosure increases the likelihood of future exploitation attempts.

1. Monitor Microsoft security advisories closely and apply patches immediately once they are released for this vulnerability. 2. Until patches are available, restrict the opening of Visio files from untrusted or unknown sources, especially via email or external downloads. 3. Implement application whitelisting and sandboxing to limit the execution scope of Visio and related processes. 4. Employ endpoint detection and response (EDR) solutions with behavior-based detection to identify suspicious activities related to memory corruption or code execution. 5. Conduct user awareness training focused on phishing and social engineering risks associated with opening unexpected or suspicious Visio files. 6. Use network segmentation to limit lateral movement if a system is compromised. 7. Regularly back up critical data and verify recovery procedures to mitigate potential data loss or ransomware scenarios stemming from exploitation. 8. Review and harden local security policies to reduce the impact of local code execution vulnerabilities.