CVE-2024-26194 is a high-severity vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). It stems from an improper verification of cryptographic signatures within the Secure Boot security feature, classified under CWE-347 (Improper Verification of Cryptographic Signature). Secure Boot is a critical security mechanism designed to ensure that only trusted, signed bootloaders and operating system components are executed during the system startup process. By bypassing this verification, an attacker could load unauthorized or malicious code early in the boot sequence, potentially gaining persistent, low-level control over the system before the OS and security software are fully operational. The CVSS v3.1 base score is 7.4, indicating a high severity with the following vector: Attack Vector: Local (AV:L), Attack Complexity: High (AC:H), Privileges Required: None (PR:N), User Interaction: None (UI:N), Scope: Unchanged (S:U), and impacts on Confidentiality, Integrity, and Availability all rated High (C:H/I:H/A:H). This means exploitation requires local access but no privileges or user interaction, and successful exploitation can fully compromise system confidentiality, integrity, and availability. No known exploits are currently reported in the wild, and no patches are listed yet. The vulnerability was reserved in February 2024 and published in April 2024. The lack of patches suggests that organizations running Windows 10 Version 1809 should consider mitigation strategies promptly to reduce risk. Given the nature of Secure Boot, exploitation could allow attackers to bypass OS-level security controls, install rootkits or bootkits, and maintain stealthy persistence, severely undermining endpoint security.

For European organizations, the impact of CVE-2024-26194 is significant, especially for those still operating legacy systems on Windows 10 Version 1809. The vulnerability undermines the foundational trust model of Secure Boot, potentially allowing attackers to execute arbitrary code at boot time, evade detection by antivirus and endpoint detection and response (EDR) solutions, and maintain persistent footholds. This can lead to full system compromise, data exfiltration, sabotage, or use of compromised systems as pivot points within corporate networks. Critical infrastructure sectors, government agencies, financial institutions, and enterprises relying on Windows 10 1809 for legacy applications are particularly at risk. The local attack vector means that attackers need some form of local access, which could be achieved via physical access, social engineering to gain local user access, or through other vulnerabilities that allow local code execution. Given the high impact on confidentiality, integrity, and availability, exploitation could disrupt business operations, cause data breaches, and damage organizational reputation. The absence of known exploits in the wild provides a window for proactive defense, but the high severity score demands urgent attention.

1. Upgrade and Patch: Although no official patch is listed yet, organizations should monitor Microsoft’s security advisories closely and apply patches immediately upon release. Consider upgrading systems from Windows 10 Version 1809 to a supported, more recent Windows version where this vulnerability is not present. 2. Limit Local Access: Since exploitation requires local access, enforce strict physical security controls and limit local user accounts with administrative privileges. 3. Use Endpoint Protection with Boot-Time Scanning: Deploy advanced endpoint security solutions capable of detecting boot-level rootkits and anomalous bootloader behavior. 4. Implement Application Control and Code Integrity Policies: Use Windows Defender Application Control (WDAC) or AppLocker to restrict execution of unauthorized code, especially at boot time. 5. Network Segmentation and Monitoring: Segment critical systems and monitor for unusual local login activity or attempts to modify boot configuration data. 6. Incident Response Preparedness: Prepare for potential exploitation by having forensic and recovery procedures ready to detect and remediate boot-level compromises. 7. Disable Legacy Boot Modes: Ensure systems are configured to use UEFI Secure Boot exclusively and disable legacy BIOS boot modes that may be more vulnerable. 8. User Awareness and Access Controls: Educate users on the risks of local access attacks and enforce strong authentication and least privilege principles to reduce attack surface.