CVE-2024-30103 is a remote code execution vulnerability identified in Microsoft Outlook, a component of Microsoft Office 2019 (version 19.0.0). The root cause is an incomplete list of disallowed inputs (CWE-184), which means Outlook fails to properly validate or block certain malicious inputs that could be used to trigger arbitrary code execution. The vulnerability allows an attacker with low privileges (PR:L) to execute code remotely over the network (AV:N) without requiring user interaction (UI:N). The scope of the vulnerability is unchanged (S:U), but it impacts confidentiality, integrity, and availability at a high level (C:H/I:H/A:H). The CVSS 3.1 base score is 8.8, indicating a high-severity issue. Although no exploits have been reported in the wild yet, the vulnerability’s characteristics make it a prime candidate for exploitation once weaponized. The vulnerability affects Microsoft Office 2019, specifically version 19.0.0, which remains widely deployed in enterprise environments. The lack of a patch link suggests that a fix is forthcoming or pending release. The vulnerability’s CWE classification (CWE-184) highlights that the issue is due to insufficient input validation or filtering, which is a common vector for remote code execution attacks in email clients. Given Outlook’s role as a primary email client in many organizations, successful exploitation could allow attackers to execute arbitrary code, potentially leading to full system compromise, data exfiltration, or disruption of services.

For European organizations, the impact of CVE-2024-30103 is significant due to the widespread use of Microsoft Office 2019 in corporate, government, and critical infrastructure sectors. A successful remote code execution attack could lead to unauthorized access to sensitive information, disruption of business operations, and potential lateral movement within networks. Confidentiality is at high risk as attackers could access emails and attachments, while integrity and availability could be compromised by malware or ransomware deployment. The lack of required user interaction increases the risk of automated exploitation campaigns. Organizations in sectors such as finance, healthcare, energy, and government are particularly vulnerable due to the sensitive nature of their data and the criticality of their services. The vulnerability could also facilitate espionage or sabotage activities, especially in the context of geopolitical tensions affecting Europe. The absence of known exploits currently provides a window for proactive mitigation, but the high CVSS score and ease of exploitation underscore the urgency of addressing this vulnerability.

1. Monitor Microsoft security advisories closely and apply official patches immediately upon release to remediate the vulnerability. 2. Until patches are available, restrict network access to Outlook services by implementing strict firewall rules and network segmentation to limit exposure. 3. Employ advanced email filtering solutions to detect and block potentially malicious inputs or attachments that could exploit this vulnerability. 4. Use endpoint detection and response (EDR) tools to monitor for suspicious behaviors indicative of exploitation attempts. 5. Enforce the principle of least privilege for user accounts to reduce the impact of potential compromise. 6. Educate users about the risks of unsolicited emails and encourage reporting of suspicious messages, even though user interaction is not required for exploitation. 7. Consider disabling or limiting legacy protocols or features in Outlook that may increase attack surface. 8. Conduct regular vulnerability assessments and penetration testing focused on email clients and related infrastructure. 9. Maintain up-to-date backups and incident response plans to quickly recover from any successful attacks. 10. Collaborate with cybersecurity information sharing groups to stay informed about emerging threats related to this vulnerability.