CVE-2025-29791 is a high-severity vulnerability classified under CWE-843 (Access of Resource Using Incompatible Type, commonly known as 'type confusion') affecting Microsoft Office 2019 version 19.0.0. This vulnerability arises from improper handling of data types within the Office application, which allows an attacker to access resources using an incompatible type. Exploiting this flaw enables an unauthorized attacker to execute arbitrary code locally on the victim's machine. The vulnerability requires the victim to interact with a maliciously crafted Office document, which triggers the type confusion bug. Once exploited, the attacker can gain elevated privileges to execute code with the same user rights as the logged-in user, potentially leading to full system compromise. The CVSS v3.1 base score is 7.8, indicating a high impact on confidentiality, integrity, and availability. The attack vector is local (AV:L), meaning the attacker must have local access or trick the user into opening a malicious file. No privileges are required (PR:N), but user interaction is necessary (UI:R). The vulnerability affects Microsoft Office 2019 specifically version 19.0.0, with no known exploits in the wild at the time of publication (April 8, 2025). No patches have been linked yet, but the vulnerability is publicly disclosed and recognized by CISA, indicating the need for prompt mitigation. Given the widespread use of Microsoft Office 2019 in enterprise environments, this vulnerability poses a significant risk if weaponized, especially in targeted attacks involving social engineering or spear-phishing campaigns.

For European organizations, the impact of CVE-2025-29791 could be substantial due to the widespread deployment of Microsoft Office 2019 across government, financial, healthcare, and industrial sectors. Successful exploitation could lead to unauthorized code execution, enabling attackers to steal sensitive data, disrupt business operations, or establish persistent footholds within networks. The local attack vector and requirement for user interaction mean that phishing campaigns remain a primary exploitation method, which is a common attack vector in Europe. Confidentiality breaches could expose personal data protected under GDPR, leading to regulatory penalties and reputational damage. Integrity and availability impacts could disrupt critical business processes, especially in sectors reliant on Office documents for daily operations. The absence of known exploits in the wild currently reduces immediate risk, but the public disclosure and high severity score necessitate proactive defenses. Organizations with remote or hybrid workforces may face increased exposure due to potential user interaction with malicious documents outside secure network environments.

European organizations should implement a multi-layered mitigation strategy beyond generic patching advice: 1) Enforce strict email filtering and attachment scanning to detect and quarantine suspicious Office documents before reaching end users. 2) Deploy and maintain advanced endpoint protection solutions capable of detecting anomalous behaviors related to type confusion exploits and code execution attempts within Office processes. 3) Implement application control policies such as Microsoft Defender Application Control or AppLocker to restrict execution of unauthorized macros or scripts embedded in Office files. 4) Conduct targeted user awareness training focusing on recognizing and avoiding phishing attempts involving malicious Office documents. 5) Utilize Microsoft Office's built-in Protected View and disable automatic enabling of macros or active content by default. 6) Monitor endpoint and network logs for unusual Office application behaviors indicative of exploitation attempts. 7) Prepare incident response playbooks specifically addressing Office-based code execution attacks. 8) Stay alert for official patches or updates from Microsoft and prioritize their deployment as soon as available. 9) Consider network segmentation to limit lateral movement if a local compromise occurs. These measures collectively reduce the likelihood of successful exploitation and limit potential damage.