CVE-2026-20824 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0) classified under CWE-693, which pertains to protection mechanism failures. Specifically, the flaw exists within the Windows Remote Assistance feature, which is designed to allow remote troubleshooting and support. This vulnerability enables a local attacker to bypass a security feature intended to protect the system, thereby gaining unauthorized access to confidential information. The attack vector is local (AV:L), meaning the attacker must have physical or logical local access to the affected system. The attack complexity is low (AC:L), and no privileges are required (PR:N), but user interaction is necessary (UI:R), such as convincing the user to perform an action that triggers the bypass. The scope remains unchanged (S:U), and the impact is primarily on confidentiality (C:H), with no impact on integrity or availability. The CVSS v3.1 base score is 5.5, indicating a medium severity level. No patches or fixes have been published yet, and there are no known exploits in the wild. The vulnerability could allow attackers to circumvent security controls that protect sensitive data accessible through Windows Remote Assistance, potentially exposing confidential information to unauthorized local users. Since the vulnerability is local and requires user interaction, exploitation is somewhat limited but still poses a risk in environments where local access controls are weak or where users may be socially engineered.

For European organizations, this vulnerability poses a risk primarily to confidentiality of sensitive data on systems running Windows 10 Version 1809. Organizations with shared or multi-user environments, such as call centers, public access terminals, or corporate desktops, could see unauthorized disclosure of information if an attacker gains local access. The lack of impact on integrity and availability reduces the risk of system disruption or data tampering. However, the requirement for local access and user interaction limits remote exploitation, making insider threats or physical access breaches more relevant. Critical sectors such as finance, healthcare, and government, where confidentiality is paramount, may face increased risk if legacy systems remain unpatched. The absence of a patch increases exposure duration, necessitating compensating controls. Overall, the impact is moderate but significant for environments with inadequate local security controls or where Windows Remote Assistance is enabled and actively used.

To mitigate this vulnerability, European organizations should first inventory and identify all systems running Windows 10 Version 1809, specifically build 10.0.17763.0. Disable Windows Remote Assistance on all systems where it is not explicitly required, as this reduces the attack surface. For systems that must retain Remote Assistance, enforce strict local access controls, including strong user authentication and session locking when unattended. Educate users to recognize and avoid social engineering attempts that could trigger the vulnerability. Implement endpoint detection and response (EDR) solutions to monitor for unusual local activity related to Remote Assistance. Restrict physical access to critical systems and consider network segmentation to limit lateral movement from compromised local accounts. Regularly review and apply security updates from Microsoft once patches become available. Additionally, consider upgrading affected systems to a supported Windows version with active security updates to reduce exposure.