CVE-2025-26633 is a high-severity vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability is categorized under CWE-707, which relates to improper neutralization of inputs or outputs, leading to security feature bypass. Specifically, this flaw exists within the Microsoft Management Console (MMC), a core Windows component used for system administration. The vulnerability allows an unauthorized local attacker to bypass security features by exploiting improper neutralization mechanisms. The CVSS v3.1 base score is 7.0, indicating a high severity level. The attack vector is local (AV:L), requiring the attacker to have local access but no privileges (PR:N). The attack complexity is high (AC:H), and user interaction is required (UI:R). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). The exploitability is functional (E:F), and the report confidence is confirmed (RC:C). No known exploits are currently reported in the wild, and no patches have been linked yet. This vulnerability could allow an attacker with local access to bypass security controls, potentially leading to unauthorized access or privilege escalation within affected systems. Given the reliance on MMC for administrative tasks, exploitation could compromise system integrity and confidentiality significantly.

For European organizations, this vulnerability poses a significant risk, especially in environments where Windows 10 Version 1809 is still in use, such as legacy systems or specialized industrial control systems. The ability to bypass security features locally could enable insider threats or attackers who have gained limited local access to escalate privileges or disable security controls, leading to data breaches, system manipulation, or disruption of critical services. This is particularly concerning for sectors with strict regulatory requirements such as finance, healthcare, and government institutions across Europe. The high impact on confidentiality, integrity, and availability means sensitive personal data protected under GDPR could be exposed or altered, resulting in legal and financial consequences. Additionally, the requirement for local access and user interaction limits remote exploitation but does not eliminate risk from compromised or malicious insiders or attackers leveraging social engineering to gain local presence.

European organizations should prioritize identifying and inventorying systems running Windows 10 Version 1809 and assess their exposure to local threat actors. Immediate mitigation steps include restricting local access to trusted users only and enforcing strict user account control policies to minimize the risk of unauthorized local access. Deploying endpoint detection and response (EDR) solutions can help detect suspicious activities related to MMC usage. Since no patches are currently linked, organizations should monitor Microsoft security advisories closely for updates and apply patches promptly once available. Additionally, implementing application whitelisting and restricting the execution of unauthorized MMC snap-ins can reduce attack surface. User training to recognize social engineering attempts that could lead to local access is also recommended. For critical systems, consider upgrading to a supported and patched Windows version to eliminate exposure to this vulnerability.