CVE-2025-26633 is a vulnerability classified under CWE-707 (Improper Neutralization) found in Microsoft Windows 10 Version 1809, specifically within the Microsoft Management Console (MMC). The flaw arises from improper input handling that allows an unauthorized local attacker to bypass security features. The vulnerability requires the attacker to have local access and to trick a user into interaction, making exploitation complex. However, successful exploitation can lead to a complete compromise of the system’s confidentiality, integrity, and availability, potentially allowing the attacker to execute arbitrary code or escalate privileges. The vulnerability affects Windows 10 Version 1809 build 10.0.17763.0, a legacy version still in use in many organizations. Although no exploits are currently known in the wild, the critical impact and the presence of legacy systems that cannot be easily upgraded increase the risk profile. The vulnerability’s CVSS v3.1 score is 7.0, reflecting high severity with attack vector local, high attack complexity, no privileges required, user interaction required, and full impact on confidentiality, integrity, and availability. Mitigation strategies focus on upgrading to supported Windows versions, applying any available patches or workarounds, and limiting local access to MMC to reduce exposure.

For European organizations, especially those in sectors such as critical infrastructure, manufacturing, and government that often rely on legacy Windows 10 1809 systems, this vulnerability poses a significant risk. Exploitation can lead to full system compromise, allowing attackers to access sensitive data, disrupt operations, or install persistent malware. The requirement for local access and user interaction limits remote exploitation but does not eliminate risk, particularly in environments with shared workstations or weak physical security controls. Legacy systems are often less monitored and patched, increasing exposure. The potential impact on confidentiality, integrity, and availability can disrupt business continuity, cause data breaches, and lead to regulatory non-compliance under GDPR and other frameworks. The lack of known exploits currently provides a window for proactive mitigation before active attacks emerge.

1. Upgrade affected systems from Windows 10 Version 1809 to a supported and patched Windows version to eliminate the vulnerability. 2. If immediate upgrade is not feasible, apply any available security patches or official workarounds provided by Microsoft as soon as they become available. 3. Restrict local access to the Microsoft Management Console (MMC) by enforcing strict user permissions and limiting MMC usage to trusted administrators only. 4. Implement robust endpoint security controls, including application whitelisting and behavior monitoring, to detect and prevent exploitation attempts. 5. Enhance physical security and access controls to prevent unauthorized local access to critical systems. 6. Conduct user awareness training to reduce the risk of social engineering that could facilitate user interaction required for exploitation. 7. Regularly audit and monitor legacy systems for unusual activity, focusing on MMC usage and privilege escalation attempts. 8. Develop and test incident response plans specifically addressing local privilege escalation and lateral movement scenarios.