CVE-2025-54907 is a heap-based buffer overflow vulnerability identified in Microsoft Office Visio 2019, specifically version 19.0.0. The flaw arises from improper handling of memory buffers on the heap during processing of certain Visio data structures, leading to potential memory corruption. An attacker with local access to the system can exploit this vulnerability by convincing a user to interact with a crafted Visio file or trigger the vulnerability through other local means. Successful exploitation allows arbitrary code execution with the privileges of the current user, potentially leading to full system compromise. The vulnerability does not require prior authentication or elevated privileges but does require user interaction, such as opening a malicious file. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. No public exploits or patches are currently available, but the vulnerability has been officially published and reserved since July 2025. This type of heap overflow (CWE-122) is a common vector for remote code execution and privilege escalation attacks, making it critical to address promptly.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Microsoft Office 2019, including Visio, in enterprise environments. Exploitation could allow attackers who gain local access—via phishing, insider threats, or compromised endpoints—to execute arbitrary code, potentially leading to data breaches, ransomware deployment, or lateral movement within networks. The high impact on confidentiality, integrity, and availability means sensitive corporate data and critical systems could be compromised. Given the requirement for local access and user interaction, the threat is more relevant in environments where endpoint security is weak or where users may be tricked into opening malicious files. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the urgency for mitigation. European sectors with high reliance on Microsoft Office, such as finance, government, and manufacturing, could face operational disruptions and reputational damage if exploited.

1. Restrict local access to systems running Microsoft Office 2019 Visio to trusted users only, minimizing exposure to potential attackers. 2. Implement strict application whitelisting and endpoint protection solutions that can detect and block exploitation attempts targeting heap overflows. 3. Educate users about the risks of opening unsolicited or suspicious Visio files, emphasizing caution with email attachments and downloads. 4. Monitor for unusual process behavior or crashes related to Visio that could indicate exploitation attempts. 5. Prepare to deploy official patches from Microsoft immediately upon release; in the meantime, consider disabling Visio if feasible or restricting its use. 6. Employ network segmentation to limit lateral movement if a local compromise occurs. 7. Use enhanced logging and endpoint detection and response (EDR) tools to identify and respond to exploitation attempts quickly.