CVE-2025-27748 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 the use of memory after it has been freed, leading to undefined behavior. In this case, an unauthorized attacker can exploit this flaw to execute arbitrary code locally on the affected system. The CVSS 3.1 base score is 7.8, 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. The attack complexity is low (AC:L), no privileges are required (PR:N), but user interaction is necessary (UI:R). The scope is unchanged (S:U), and the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). The exploitability is currently unknown in the wild, and no patches have been linked yet. The vulnerability arises because the application attempts to use memory that has already been freed, which can lead to memory corruption, crashes, or arbitrary code execution. This can be triggered by opening a specially crafted document or performing specific actions within Office 2019. Given the nature of the vulnerability, it could be leveraged by attackers to escalate privileges or execute malicious payloads on a compromised machine.

For European organizations, this vulnerability poses a significant risk, especially in environments where Microsoft Office 2019 is widely deployed. The ability for an attacker to execute code locally can lead to lateral movement within corporate networks, data exfiltration, or deployment of ransomware and other malware. Since the attack requires local access and user interaction, phishing campaigns or social engineering could be used to trick users into opening malicious documents, a common attack vector in Europe. The high impact on confidentiality, integrity, and availability means sensitive data could be compromised, business operations disrupted, and regulatory compliance (such as GDPR) violated, potentially resulting in legal and financial repercussions. Organizations with critical infrastructure or sensitive data processing are particularly vulnerable to targeted exploitation.

Organizations should prioritize deploying official patches from Microsoft as soon as they become available. In the interim, practical mitigations include disabling macros and ActiveX controls in Office documents, enforcing strict email filtering to block or quarantine suspicious attachments, and educating users about the risks of opening unsolicited or unexpected documents. Application whitelisting can prevent unauthorized code execution, and endpoint detection and response (EDR) solutions should be tuned to detect anomalous Office process behaviors. Restricting local user privileges can limit the impact of exploitation. Additionally, organizations should monitor for unusual activity on endpoints and network segments where Office 2019 is used. Regular backups and incident response plans should be updated to prepare for potential exploitation scenarios.