CVE-2025-53740 is a high-severity use-after-free vulnerability identified in Microsoft Office 2019, specifically version 19.0.0. This vulnerability is classified under CWE-416, which refers to use-after-free errors where a program continues to use memory after it has been freed, potentially leading to arbitrary code execution. In this case, the flaw allows an unauthorized attacker to execute code locally on the affected system without requiring any user interaction or privileges. The CVSS v3.1 base score is 8.4, reflecting a high impact on confidentiality, integrity, and availability. The attack vector is local (AV:L), meaning the attacker must have local access to the system, but no privileges (PR:N) or user interaction (UI:N) are required, which increases the threat level. The vulnerability is exploitable with low attack complexity (AC:L), and the scope is unchanged (S:U), indicating the impact is confined to the vulnerable component. The exploit could allow complete compromise of the affected system, including full control over data and system processes. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating this is a newly disclosed vulnerability. The lack of required user interaction and privileges makes it particularly dangerous in environments where local access might be possible, such as shared workstations or compromised user accounts.

For European organizations, this vulnerability poses a significant risk, especially in sectors heavily reliant on Microsoft Office 2019 for daily operations, such as finance, government, healthcare, and legal services. Successful exploitation could lead to unauthorized code execution, enabling attackers to install malware, steal sensitive data, or disrupt business operations. Given the high confidentiality, integrity, and availability impacts, organizations could face data breaches, operational downtime, and reputational damage. The local attack vector means that insider threats or attackers who gain limited local access could leverage this vulnerability without needing elevated privileges or user interaction, increasing the risk in environments with shared or poorly secured endpoints. Additionally, the absence of a patch at the time of disclosure means organizations must act quickly to implement mitigations to reduce exposure. The vulnerability could also be chained with other exploits to achieve remote code execution, amplifying its threat potential.

European organizations should immediately audit and restrict local access to systems running Microsoft Office 2019, ensuring that only trusted users have physical or remote desktop access. Implement strict endpoint security controls, including application whitelisting and behavior-based detection to identify anomalous activities indicative of exploitation attempts. Employ network segmentation to limit lateral movement if a local compromise occurs. Regularly back up critical data and verify restore procedures to mitigate potential data loss. Monitor system logs and security alerts for unusual activity related to Office processes. Until an official patch is released, consider disabling or restricting the use of vulnerable Office components or features if feasible. Educate users about the risks of local access and enforce strong authentication mechanisms to reduce the likelihood of unauthorized local access. Finally, stay updated with Microsoft’s security advisories to apply patches promptly once available.