CVE-2025-27745 is a high-severity use-after-free vulnerability (CWE-416) identified in Microsoft Office 2019, specifically version 19.0.0. This vulnerability allows an unauthorized attacker to execute arbitrary code locally on the affected system. 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 code execution. In this case, the flaw exists within Microsoft Office 2019, a widely used productivity suite. Exploitation requires local access and some user interaction, such as opening a maliciously crafted Office document. The CVSS 3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. The vulnerability is exploitable without elevated privileges but does require user interaction, such as opening a document. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability was reserved in early March 2025 and published in April 2025, indicating recent discovery. Given the critical role of Microsoft Office in enterprise environments, this vulnerability poses a significant risk if exploited, potentially allowing attackers to execute arbitrary code, escalate privileges, or disrupt operations on affected machines.

For European organizations, the impact of CVE-2025-27745 can be substantial. Microsoft Office 2019 is extensively used across European businesses, government agencies, and educational institutions, making the attack surface large. Successful exploitation could lead to unauthorized code execution, enabling attackers to install malware, steal sensitive data, or disrupt business processes. This could compromise confidentiality of personal and corporate data, integrity of documents and communications, and availability of critical office applications. Given the local attack vector and requirement for user interaction, phishing campaigns or malicious document distribution remain likely attack vectors. The vulnerability could be leveraged in targeted attacks against high-value European targets, including financial institutions, healthcare providers, and public sector organizations, where data sensitivity and regulatory compliance (e.g., GDPR) are paramount. The absence of known exploits currently provides a window for proactive mitigation, but the high severity score underscores the urgency for organizations to prepare defenses.

European organizations should implement a multi-layered mitigation strategy beyond generic patching advice. First, they should monitor Microsoft’s security advisories closely and apply official patches immediately upon release. Until patches are available, organizations should enforce strict email filtering and attachment scanning to block or quarantine suspicious Office documents. User awareness training should emphasize the risks of opening unsolicited or unexpected Office files, particularly from unknown sources. Application control policies can restrict execution of untrusted macros or scripts within Office documents. Endpoint detection and response (EDR) tools should be tuned to detect anomalous behaviors indicative of exploitation attempts, such as unusual memory access patterns or process injections. Network segmentation can limit lateral movement if a device is compromised. Additionally, organizations should audit and harden local user privileges to minimize impact if code execution occurs. Regular backups and incident response plans should be updated to address potential exploitation scenarios. Finally, leveraging Microsoft Defender for Office 365 and advanced threat protection solutions can provide additional layers of defense against malicious documents.