CVE-2026-20832 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 17763.0) affecting the Remote Procedure Call (RPC) Interface Definition Language (IDL) component. The root cause is a double free condition (CWE-415), where the system attempts to free the same memory twice, leading to memory corruption. This flaw can be exploited by a local attacker with limited privileges (PR:L) to elevate their privileges to SYSTEM level without requiring user interaction (UI:N). The attack vector is local (AV:L), meaning the attacker must have access to the system already, but the vulnerability allows them to bypass normal privilege restrictions. The vulnerability impacts confidentiality, integrity, and availability (all rated high), as an attacker gaining SYSTEM privileges can execute arbitrary code, access sensitive data, and disrupt system operations. The CVSS v3.1 base score is 7.8, reflecting high severity. No public exploits have been reported yet, but the vulnerability is published and known. The lack of a patch link indicates that a fix may be pending or not yet publicly released. The vulnerability is significant because Windows 10 Version 1809 remains in use in some enterprise and government environments, particularly where legacy systems persist. The double free issue in the RPC IDL component is critical because RPC is a core Windows service used for inter-process communication, and its compromise can lead to widespread system control.

For European organizations, this vulnerability poses a serious risk, especially those still running Windows 10 Version 1809 in production environments. Successful exploitation can lead to full system compromise, allowing attackers to access confidential data, modify system configurations, and disrupt availability of critical services. This is particularly concerning for sectors such as government, finance, healthcare, and critical infrastructure, where Windows 10 1809 may still be deployed due to legacy application dependencies. The elevation of privilege can facilitate lateral movement within networks, increasing the risk of broader compromise. Additionally, the local attack vector means insider threats or attackers who gain initial foothold via other means can leverage this vulnerability to escalate privileges. The absence of known exploits reduces immediate risk but does not eliminate it, as attackers may develop exploits once the vulnerability details are widely known. Organizations failing to update or mitigate this vulnerability face increased risk of targeted attacks and potential regulatory consequences under GDPR if data breaches occur.

Organizations should prioritize upgrading from Windows 10 Version 1809 to a supported, patched version of Windows 10 or Windows 11 to eliminate exposure. Until patches are available, implement strict local access controls to limit user permissions and restrict access to systems running the vulnerable OS. Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor for suspicious local activity indicative of privilege escalation attempts. Disable or restrict RPC services where feasible, especially on systems not requiring RPC functionality. Conduct regular audits of user privileges and remove unnecessary local administrator rights. Network segmentation can limit lateral movement if compromise occurs. Maintain up-to-date backups and incident response plans to quickly recover from potential attacks. Monitor threat intelligence sources for any emerging exploit code targeting this vulnerability to enable rapid response. Finally, educate users and administrators about the risks of local privilege escalation vulnerabilities and the importance of timely patching and system upgrades.