CVE-2026-20936 is a security vulnerability classified as CWE-125 (Out-of-bounds Read) found in the Microsoft Windows 10 Version 1809 NDIS component. NDIS is a core networking driver interface responsible for managing network communications. The vulnerability allows an attacker with authorized access and physical presence to perform an out-of-bounds read operation, which can lead to unauthorized disclosure of sensitive information from system memory. The attack vector requires physical access to the device, making remote exploitation infeasible. The vulnerability does not require user interaction but does require low privileges (PR:L) on the system. The CVSS v3.1 score of 4.3 reflects a medium severity, primarily due to the limited attack vector (physical access) and the impact being limited to confidentiality (disclosure of information) without affecting integrity or availability. No known exploits have been reported in the wild, and no official patches have been linked yet, indicating that mitigation may currently rely on system upgrades or physical security controls. This vulnerability is particularly relevant for environments where devices running Windows 10 Version 1809 are accessible to potentially malicious insiders or attackers with physical access, such as in shared office spaces, public kiosks, or poorly secured facilities.

For European organizations, the primary impact of CVE-2026-20936 is the potential unauthorized disclosure of sensitive information due to out-of-bounds memory reads on affected Windows 10 Version 1809 devices. This can compromise confidentiality of data processed or stored on these systems. Sectors such as government, finance, healthcare, and critical infrastructure that may still operate legacy Windows 10 systems are at heightened risk, especially if physical security controls are weak. The requirement for physical access limits the scope of exploitation but does not eliminate risk in environments with shared or public device access. The vulnerability does not affect system integrity or availability, so operational disruption is unlikely. However, information disclosure could facilitate further targeted attacks or data breaches. Organizations with compliance obligations under GDPR must consider the risk of data exposure and potential regulatory consequences if sensitive personal data is compromised.

1. Upgrade affected systems from Windows 10 Version 1809 to a supported and patched Windows version to eliminate the vulnerability. 2. Enforce strict physical security controls to prevent unauthorized physical access to devices, including secure storage, access logging, and surveillance. 3. Implement device encryption (e.g., BitLocker) to protect data at rest, reducing the value of information accessible via out-of-bounds reads. 4. Monitor and audit access to sensitive systems, especially in environments with shared or public device usage. 5. Restrict user privileges to the minimum necessary to reduce the risk posed by authorized attackers. 6. Stay informed on official Microsoft advisories for patches or workarounds related to this vulnerability. 7. Consider network segmentation to isolate legacy systems and limit exposure. 8. Educate staff on the risks of physical device access and enforce policies to prevent unauthorized handling of devices.