CVE-2025-62553 is a use-after-free vulnerability identified in Microsoft Office Excel 2019, specifically version 19.0.0. This vulnerability is categorized under CWE-416, which involves the use of memory after it has been freed, leading to undefined behavior. In this case, the flaw allows an unauthorized attacker to execute arbitrary code locally on the affected system. The vulnerability does not require any privileges or authentication but does require user interaction, such as opening a malicious Excel file. The CVSS 3.1 base score is 7.8, indicating a high severity level, with metrics AV:L (local attack vector), AC:L (low attack complexity), PR:N (no privileges required), UI:R (user interaction required), and impacts on confidentiality, integrity, and availability all rated high. The vulnerability was reserved on 2025-10-15 and published on 2025-12-09. No public exploits are known at this time, but the potential for local code execution could allow attackers to escalate privileges or move laterally within a network. The lack of available patches at the time of reporting necessitates immediate attention to mitigation strategies. This vulnerability affects a widely used productivity suite, increasing its potential impact across various sectors.

For European organizations, this vulnerability presents a significant risk due to the widespread use of Microsoft Office 2019 in enterprise, government, and educational environments. Successful exploitation could lead to local code execution, allowing attackers to compromise sensitive data, alter or destroy information, and disrupt business operations. The high impact on confidentiality, integrity, and availability means that critical data and systems could be exposed or damaged. Given that exploitation requires local access and user interaction, insider threats or social engineering attacks (e.g., phishing with malicious Excel attachments) are plausible attack vectors. The vulnerability could facilitate lateral movement within networks, increasing the risk of broader compromise. Organizations in sectors such as finance, healthcare, and government, which handle sensitive personal and operational data, are particularly vulnerable. The absence of known exploits currently provides a window for proactive defense, but the high severity score underscores the urgency of mitigation.

1. Monitor Microsoft security advisories closely and apply official patches immediately once released for Microsoft Office 2019 version 19.0.0. 2. Implement strict application control policies to restrict execution of untrusted or unsigned macros and Excel files. 3. Employ endpoint protection solutions capable of detecting anomalous behavior related to use-after-free exploitation. 4. Educate users on the risks of opening unsolicited or unexpected Excel attachments, emphasizing phishing awareness. 5. Limit local administrative privileges and restrict access to systems running Office 2019 to reduce the attack surface. 6. Use network segmentation to contain potential lateral movement if a local compromise occurs. 7. Regularly audit and monitor logs for suspicious activity related to Office applications. 8. Consider deploying sandboxing or application isolation technologies to contain potential exploits. These measures, combined with timely patching, will reduce the risk posed by this vulnerability.