CVE-2024-37975 is a high-severity integer underflow vulnerability (CWE-191) affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability specifically targets the Secure Boot security feature, which is designed to ensure that only trusted software is loaded during the system boot process. An integer underflow occurs when an arithmetic operation causes a value to wrap around below its minimum representable value, potentially leading to unexpected behavior or security bypasses. In this case, the underflow can be exploited to bypass Secure Boot protections, allowing an attacker to load unauthorized or malicious code during system startup. The CVSS 3.1 base score is 8.0, indicating a high severity level. The vector string (AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) reveals that the attack requires adjacent network access (AV:A), low attack complexity (AC:L), no privileges (PR:N), but requires user interaction (UI:R). The scope is unchanged (S:U), and the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits are currently reported in the wild, and no patches have been linked yet. This vulnerability is critical because Secure Boot is a foundational security mechanism that prevents rootkits and bootkits, and bypassing it can lead to persistent, stealthy compromise of the system at a very low level. The vulnerability's exploitation could allow attackers to execute arbitrary code with high privileges early in the boot process, undermining the trustworthiness of the entire operating system environment.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and government agencies relying on Windows 10 Version 1809 in environments where Secure Boot is enabled as a security baseline. Successful exploitation could lead to persistent malware infections that survive OS reinstalls or antivirus scans, enabling espionage, data theft, or sabotage. Critical infrastructure sectors such as finance, healthcare, energy, and public administration could be targeted due to the high impact on confidentiality, integrity, and availability. The requirement for user interaction and adjacent network access somewhat limits remote exploitation but does not eliminate risk in environments with internal threat actors or phishing vectors. Legacy systems that have not been upgraded from Windows 10 Version 1809 remain vulnerable, and given that many European organizations maintain extended support for legacy systems, the threat is material. The lack of a patch at the time of disclosure increases the window of exposure. Additionally, bypassing Secure Boot undermines hardware-rooted security assurances, potentially affecting compliance with European cybersecurity regulations such as NIS2 and GDPR if breaches occur.

European organizations should prioritize the following mitigations: 1) Immediate inventory and identification of systems running Windows 10 Version 1809 with Secure Boot enabled. 2) Apply any forthcoming security patches from Microsoft as soon as they are released; monitor official Microsoft security advisories closely. 3) Until patches are available, consider disabling Secure Boot only as a temporary measure in controlled environments, understanding this reduces overall system security. 4) Implement strict network segmentation and limit adjacent network access to vulnerable systems to reduce exposure. 5) Enhance user awareness training to prevent social engineering or phishing attempts that could trigger user interaction required for exploitation. 6) Employ endpoint detection and response (EDR) solutions capable of detecting anomalous boot-time behaviors or unauthorized firmware modifications. 7) Plan and execute upgrades to supported Windows versions beyond 1809 to reduce exposure to legacy vulnerabilities. 8) Review and strengthen physical security controls to prevent local attacker access, as local interaction may facilitate exploitation. 9) Conduct regular security audits and penetration testing focusing on boot integrity and firmware security to detect potential bypass attempts.