CVE-2026-20824 is a vulnerability classified under CWE-693 (Protection Mechanism Failure) affecting Microsoft Windows 10 Version 1809 (build 17763.0). The issue resides in the Windows Remote Assistance feature, where a protection mechanism can be bypassed by an unauthorized local attacker. This bypass allows the attacker to circumvent security controls designed to protect sensitive operations or data confidentiality on the affected system. The vulnerability does not require privileges (PR:N) but does require user interaction (UI:R), indicating that some form of user action, such as accepting a prompt or opening a file, is necessary for exploitation. The attack vector is local (AV:L), meaning the attacker must have physical or logical local access to the machine. The vulnerability impacts confidentiality (C:H) but does not affect integrity or availability. No known exploits have been reported in the wild, and no patches are currently linked, although Microsoft is expected to release updates. The vulnerability's medium severity (CVSS 5.5) reflects the moderate risk posed by the combination of local access and user interaction requirements. This flaw could be leveraged to gain unauthorized access to sensitive information or bypass security controls that rely on Remote Assistance protections, potentially facilitating further attacks or data leakage.

For European organizations, the impact of CVE-2026-20824 primarily concerns confidentiality breaches on systems running Windows 10 Version 1809. Organizations in sectors such as government, finance, healthcare, and critical infrastructure that still operate legacy Windows 10 builds may face risks of unauthorized local access leading to sensitive data exposure. The requirement for local access and user interaction limits remote exploitation but does not eliminate insider threat risks or risks from compromised endpoints. Confidentiality loss could lead to data leaks, regulatory non-compliance (e.g., GDPR), and reputational damage. Since integrity and availability are not affected, the threat does not directly disrupt operations but could be a stepping stone for further attacks. The absence of known exploits reduces immediate risk but does not preclude future weaponization. European entities with legacy system dependencies or insufficient endpoint security controls are most vulnerable.

1. Apply security updates from Microsoft promptly once patches for CVE-2026-20824 are released. 2. Until patches are available, disable Windows Remote Assistance on systems running Windows 10 Version 1809 if it is not required operationally. 3. Restrict local access to sensitive systems through physical security controls and endpoint access management to prevent unauthorized users from exploiting the vulnerability. 4. Implement strict user training and awareness programs to reduce risky user interactions that could trigger exploitation. 5. Employ endpoint detection and response (EDR) solutions to monitor for suspicious local activities related to Remote Assistance. 6. Consider upgrading affected systems to supported, fully patched Windows versions to eliminate exposure to legacy vulnerabilities. 7. Audit and enforce least privilege principles to limit user capabilities on affected machines. 8. Monitor security advisories from Microsoft and threat intelligence sources for emerging exploit information.