CVE-2025-53740 is a high-severity use-after-free vulnerability identified in Microsoft Office 2019 version 19.0.0. The vulnerability arises from improper handling of memory within the Office suite, where a previously freed memory object is accessed again, leading to undefined behavior. This flaw can be exploited by an unauthorized attacker to execute arbitrary code locally on the affected system without requiring user interaction or prior authentication. The CVSS 3.1 base score of 8.4 reflects the critical impact on confidentiality, integrity, and availability, with the attack vector being local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The vulnerability affects the confidentiality, integrity, and availability of the system, allowing an attacker to gain control over the affected machine. Although no known exploits are currently reported in the wild, the vulnerability's nature and impact make it a significant risk. The lack of available patches at the time of publication increases the urgency for mitigation. This vulnerability is categorized under CWE-416 (Use After Free), a common memory corruption issue that can lead to arbitrary code execution, system crashes, or data corruption. Given Microsoft Office's widespread use in enterprise and government environments, this vulnerability poses a substantial risk to organizations relying on Office 2019 for daily operations.

For European organizations, the impact of CVE-2025-53740 could be severe. Microsoft Office 2019 is extensively used across various sectors including finance, healthcare, government, and education. Exploitation of this vulnerability could allow attackers to execute arbitrary code locally, potentially leading to data breaches, ransomware deployment, or disruption of critical business functions. The ability to execute code without user interaction or privileges increases the risk of automated or insider attacks. Confidentiality breaches could expose sensitive personal and corporate data, violating GDPR and other data protection regulations, leading to legal and financial penalties. Integrity and availability impacts could disrupt business continuity, affecting service delivery and operational efficiency. The vulnerability's local attack vector means that attackers would need some form of local access, which could be gained through phishing, malicious insiders, or compromised endpoints. This elevates the risk in environments where endpoint security is weak or where users have elevated privileges. Overall, the vulnerability could undermine trust in IT infrastructure and necessitate urgent incident response and remediation efforts.

Given the absence of an official patch at the time of reporting, European organizations should implement immediate compensating controls. These include restricting local access to systems running Microsoft Office 2019 by enforcing strict endpoint security policies and limiting user privileges to the minimum necessary. Employ application whitelisting to prevent execution of unauthorized code and use advanced endpoint detection and response (EDR) tools to monitor for suspicious activity indicative of exploitation attempts. Network segmentation can limit lateral movement if a system is compromised. Organizations should also educate users about the risks of local attacks and enforce strong physical security controls to prevent unauthorized device access. Regularly update and audit software inventories to identify and prioritize vulnerable systems. Once Microsoft releases a security update, organizations must prioritize its deployment across all affected systems. Additionally, consider upgrading to supported versions of Microsoft Office that receive regular security updates. Incident response plans should be reviewed and tested to ensure readiness in case of exploitation.