CVE-2024-26171 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0) related to an integer overflow or wraparound issue (CWE-190) within the Secure Boot security feature. Secure Boot is a critical security mechanism designed to ensure that a device boots using only software trusted by the Original Equipment Manufacturer (OEM). This vulnerability allows a potential security feature bypass, meaning that an attacker with sufficient privileges could exploit the integer overflow flaw to circumvent Secure Boot protections. The integer overflow likely occurs during the processing of certain data values related to Secure Boot validation, causing incorrect calculations or memory handling that can be manipulated to bypass security checks. The CVSS 3.1 base score is 6.7, indicating a medium severity level. The vector string (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H) shows that the attack requires local access (AV:L), low attack complexity (AC:L), and high privileges (PR:H), with no user interaction (UI:N). The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning successful exploitation could lead to full compromise of system security, including unauthorized code execution during boot, potentially persistent malware installation, and complete system control. No known exploits in the wild have been reported yet, and no patches are currently linked, indicating that mitigation may rely on vendor updates or workarounds. This vulnerability affects a specific legacy Windows 10 version (1809), which is still in use in some enterprise environments but is no longer the latest supported version. The integer overflow nature of the flaw suggests that it could be triggered by crafted inputs or data structures processed during the Secure Boot process, potentially by malicious firmware or local attackers with administrative privileges.

For European organizations, the impact of CVE-2024-26171 is significant primarily in environments still running Windows 10 Version 1809, especially in sectors where legacy systems are maintained for compatibility or regulatory reasons. Successful exploitation could allow attackers to bypass Secure Boot protections, undermining the root of trust in system integrity and enabling persistent, stealthy malware infections that survive reboots and evade detection by traditional security controls. This could lead to data breaches, espionage, or sabotage, particularly in critical infrastructure, government, finance, and industrial sectors. The requirement for high privileges and local access limits remote exploitation but does not eliminate risk, as insider threats or lateral movement within networks could leverage this vulnerability to escalate control. The absence of user interaction means that once an attacker has the necessary access, exploitation can be fully automated and stealthy. Given the high impact on confidentiality, integrity, and availability, organizations relying on affected systems face risks of severe operational disruption and data compromise. Additionally, the lack of a current patch increases exposure until mitigations or updates are applied.

1. Immediate inventory and identification of all systems running Windows 10 Version 1809 within the organization to assess exposure. 2. Prioritize upgrading or migrating affected systems to a supported and patched Windows version where this vulnerability is not present or has been addressed. 3. Restrict administrative and local access privileges strictly to trusted personnel and implement robust access controls and monitoring to detect unauthorized privilege escalations. 4. Employ hardware-based security features such as Trusted Platform Module (TPM) and enable additional firmware protections where possible to reinforce Secure Boot integrity. 5. Monitor system logs and firmware integrity checks for anomalies that could indicate attempts to exploit Secure Boot bypass. 6. Coordinate with Microsoft and subscribe to security advisories to apply patches or workarounds as soon as they become available. 7. Implement endpoint detection and response (EDR) solutions capable of detecting suspicious behavior related to boot processes and firmware tampering. 8. Conduct regular security awareness training emphasizing the risks of local privilege abuse and insider threats. 9. For critical systems where upgrade is not immediately feasible, consider isolating them from broader network access to reduce attack surface. 10. Validate Secure Boot configurations and firmware versions to ensure they conform to security best practices and have not been tampered with.