CVE-2025-54907 is a heap-based buffer overflow vulnerability identified in Microsoft Office Visio 2019 (version 19.0.0). This vulnerability arises from improper handling of memory buffers within Visio, allowing an attacker to overflow a heap buffer and overwrite adjacent memory. Exploitation requires the victim to open a specially crafted Visio file, which triggers the overflow and enables execution of arbitrary code with the privileges of the user running the application. The vulnerability does not require prior authentication or elevated privileges, but does require user interaction (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. Although no public exploits are known at this time, the vulnerability poses a significant risk due to the widespread use of Microsoft Office 2019 in enterprise environments. The flaw is categorized under CWE-122 (Heap-based Buffer Overflow), a common and dangerous class of memory corruption vulnerabilities that can lead to arbitrary code execution and system compromise. The vulnerability was reserved on July 31, 2025, and published on September 9, 2025, but no patch links have been provided yet, indicating that remediation may still be pending or in progress.

For European organizations, this vulnerability presents a substantial risk, particularly in sectors that rely heavily on Microsoft Office Visio for business processes, such as engineering, architecture, finance, and government. Successful exploitation could lead to local code execution, enabling attackers to install malware, steal sensitive data, or disrupt operations. The high confidentiality, integrity, and availability impacts mean that data breaches or operational disruptions could occur. Given the requirement for user interaction, phishing or social engineering campaigns could be used to deliver malicious Visio files. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits rapidly after disclosure. Organizations with large deployments of Office 2019, particularly in countries with high Microsoft market share and advanced industrial sectors, face elevated exposure. The potential for lateral movement and privilege escalation exists if attackers gain initial footholds via this vulnerability.

Organizations should prioritize monitoring Microsoft security advisories for the release of official patches addressing CVE-2025-54907 and apply them immediately upon availability. Until patches are released, restrict the opening of Visio files from untrusted or unknown sources through email filtering, endpoint controls, and user education to reduce the risk of exploitation. Implement application whitelisting and sandboxing to limit the execution of unauthorized code. Employ advanced endpoint detection and response (EDR) solutions capable of detecting anomalous behavior indicative of heap overflow exploitation. Network segmentation can help contain potential compromises. Additionally, enforce the principle of least privilege for users to minimize the impact of any successful exploitation. Regularly back up critical data and test recovery procedures to mitigate potential availability impacts. Security awareness training should emphasize the risks of opening unsolicited or suspicious Visio documents.