CVE-2025-49734 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 17763.0) related to improper restriction of communication channels within Windows PowerShell, classified under CWE-923. This vulnerability arises because the communication channel used by PowerShell does not adequately restrict connections to intended endpoints, allowing an attacker with local, low-privilege access to communicate with unintended endpoints. Exploiting this flaw enables the attacker to elevate their privileges on the system without requiring user interaction, thereby gaining higher-level access than originally permitted. The vulnerability affects confidentiality, integrity, and availability by potentially allowing unauthorized access to sensitive data, modification of system configurations, or disruption of services. The CVSS v3.1 base score is 7.0, reflecting high severity due to the local attack vector, high impact on system security properties, and the requirement for low privileges but no user interaction. Although no public exploits are known yet, the vulnerability's nature suggests that attackers with local access could leverage it to bypass security controls. The lack of available patches at the time of publication necessitates immediate attention to alternative mitigations. This vulnerability is particularly concerning for environments where Windows 10 Version 1809 remains in use, especially in enterprise or critical infrastructure settings where PowerShell is commonly employed for automation and management tasks.

For European organizations, the impact of CVE-2025-49734 can be significant, especially in sectors relying heavily on Windows 10 Version 1809, such as government, finance, healthcare, and critical infrastructure. Successful exploitation could lead to unauthorized privilege escalation, enabling attackers to execute arbitrary code with elevated rights, access sensitive information, or disrupt system operations. This could result in data breaches, operational downtime, and compromise of critical services. Given that the vulnerability requires local access, insider threats or attackers who have already gained limited footholds could leverage this to deepen their control. The high confidentiality, integrity, and availability impacts increase the risk profile for organizations handling sensitive personal data under GDPR, potentially leading to regulatory penalties and reputational damage. Additionally, legacy systems that have not been updated or replaced remain vulnerable, increasing the attack surface within European enterprises.

1. Apply official patches from Microsoft as soon as they become available to address the vulnerability directly. 2. Until patches are released, restrict local access to systems running Windows 10 Version 1809 by enforcing strict access controls and limiting user privileges. 3. Implement application whitelisting and restrict PowerShell usage to trusted scripts and administrators only. 4. Monitor PowerShell logs and system event logs for unusual or unauthorized activity indicative of privilege escalation attempts. 5. Employ endpoint detection and response (EDR) solutions capable of detecting anomalous PowerShell behavior. 6. Consider upgrading affected systems to a supported and patched version of Windows to reduce exposure. 7. Conduct regular security awareness training emphasizing the risks of local privilege escalation and insider threats. 8. Use network segmentation to isolate critical systems and limit lateral movement opportunities for attackers with local access.