CVE-2025-30377 is a high-severity use-after-free vulnerability identified in Microsoft Office 2019, specifically version 19.0.0. The vulnerability is classified under CWE-416, which involves improper handling of memory that has already been freed, leading to potential exploitation. In this case, an unauthorized attacker can leverage this flaw to execute arbitrary code locally on the affected system without requiring any privileges or user interaction. 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 needed, which increases the risk if local access is gained through other means. The vulnerability allows complete compromise of the affected system, as it can lead to full code execution with high impact on all security properties. No known exploits are currently reported in the wild, but the vulnerability is publicly disclosed and patched links are not yet available, indicating the need for immediate attention. The flaw arises from improper memory management in Microsoft Office 2019, which could be triggered by opening or processing maliciously crafted Office documents, potentially leading to system compromise.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Microsoft Office 2019 across enterprises, government agencies, and critical infrastructure sectors. Successful exploitation could allow attackers to execute arbitrary code locally, potentially leading to data breaches, ransomware deployment, or lateral movement within networks. The lack of required privileges or user interaction lowers the barrier for exploitation once local access is obtained, which could be achieved through other attack vectors such as phishing, insider threats, or compromised endpoints. Confidentiality, integrity, and availability of sensitive information and systems could be severely impacted, disrupting business operations and causing financial and reputational damage. Sectors such as finance, healthcare, and public administration, which heavily rely on Office productivity tools, are particularly vulnerable. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as threat actors may develop exploits rapidly following public disclosure.

European organizations should prioritize the following specific mitigation steps: 1) Immediately inventory and identify all systems running Microsoft Office 2019 version 19.0.0 to assess exposure. 2) Monitor official Microsoft security advisories closely for the release of patches or updates addressing CVE-2025-30377 and apply them promptly once available. 3) Implement application whitelisting and restrict execution of untrusted Office macros or scripts to reduce the risk of exploitation via malicious documents. 4) Employ endpoint detection and response (EDR) solutions to detect anomalous behaviors indicative of exploitation attempts, such as unusual memory access patterns or process injections. 5) Enforce strict access controls and network segmentation to limit local access opportunities for attackers, minimizing the risk of local exploitation. 6) Educate users on safe handling of Office documents, especially those received from untrusted sources, to reduce the likelihood of opening malicious files. 7) Consider deploying sandboxing or document inspection technologies that can analyze Office files for malicious content before delivery to end users. These targeted measures go beyond generic patching advice and address the specific exploitation vectors and operational context of this vulnerability.