CVE-2026-20864 is a heap-based buffer overflow vulnerability identified in the Connected Devices Platform Service (Cdpsvc) component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability arises from improper handling of memory buffers, allowing an attacker with authorized local access to overflow a heap buffer, which can corrupt memory and lead to arbitrary code execution with elevated privileges. This flaw enables privilege escalation from a low-privileged user to SYSTEM level, compromising the confidentiality, integrity, and availability of the affected system. The vulnerability does not require user interaction but does require local access and existing privileges, making it a post-compromise risk that can facilitate lateral movement or persistence within a network. The CVSS v3.1 score of 7.8 reflects high severity due to the impact on all security properties and relatively low attack complexity. No public exploits have been reported yet, but the vulnerability is critical for environments still running this older Windows 10 version, which is no longer mainstream supported. The lack of available patches at the time of reporting increases the urgency for mitigation through access control and monitoring.

For European organizations, this vulnerability poses a significant risk particularly in sectors where legacy Windows 10 Version 1809 systems remain operational, such as manufacturing, healthcare, and government agencies with slower upgrade cycles. Successful exploitation can lead to full system compromise, allowing attackers to access sensitive data, disrupt operations, or move laterally within corporate networks. The elevation of privileges can bypass existing security controls, undermining endpoint protection and increasing the risk of ransomware or espionage attacks. Given the high impact on confidentiality, integrity, and availability, organizations could face data breaches, operational downtime, and regulatory penalties under GDPR if personal data is exposed. The threat is amplified in environments with shared or weakly controlled local access, such as shared workstations or remote desktop services. Although no exploits are currently known in the wild, the vulnerability’s characteristics make it a likely target for attackers once exploit code becomes available.

1. Prioritize upgrading affected systems to a supported and patched version of Windows 10 or later to eliminate the vulnerability. 2. Until patches are available, restrict local access to systems running Windows 10 Version 1809, enforcing strict user account controls and limiting administrative privileges. 3. Implement application whitelisting and endpoint detection and response (EDR) solutions to monitor for unusual behavior indicative of privilege escalation attempts. 4. Harden the Connected Devices Platform Service by disabling it if not required or applying restrictive Group Policy settings to limit its exposure. 5. Conduct regular audits of user permissions and remove unnecessary local accounts to reduce the attack surface. 6. Employ network segmentation to contain potential lateral movement from compromised endpoints. 7. Monitor security logs for signs of heap corruption or Cdpsvc anomalies. 8. Educate IT staff on the risks of legacy systems and the importance of timely patch management.