CVE-2026-20834 is a medium-severity absolute path traversal vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw resides in the Windows Shell component, which improperly handles file paths, allowing an attacker with physical access to the device to perform spoofing attacks by manipulating absolute file paths. This vulnerability is categorized under CWE-36 (Absolute Path Traversal), where an attacker can influence file path inputs to access unintended files or directories. The vulnerability does not require any privileges or user interaction, but exploitation is limited to scenarios where the attacker can physically interact with the device, such as inserting malicious media or manipulating the file system directly. The CVSS v3.1 score of 4.6 reflects a medium severity level, with attack vector being physical (AV:P), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). The impact primarily affects confidentiality, potentially allowing unauthorized disclosure of sensitive information through spoofed file paths or misleading file system representations. There are no known exploits in the wild, and no patches have been released yet, increasing the importance of preventive measures. The vulnerability is specific to Windows 10 Version 1809, which is an older Windows release, often still in use in legacy environments. The lack of integrity or availability impact reduces the overall severity but does not eliminate risk, especially in environments where physical security is weak or devices are accessible to untrusted individuals.

For European organizations, this vulnerability poses a moderate risk primarily in environments where physical access to Windows 10 Version 1809 devices is possible, such as shared workspaces, public kiosks, or remote offices with less stringent physical security. The confidentiality impact could lead to unauthorized disclosure of sensitive file paths or data, potentially aiding further attacks or data leakage. Critical infrastructure sectors, government agencies, and enterprises with legacy systems running this Windows version are at higher risk. The lack of known exploits and the physical access requirement limit widespread exploitation but do not eliminate targeted attacks, especially in high-value environments. Organizations relying on Windows 10 Version 1809 should consider the risk of insider threats or physical tampering. The vulnerability could also complicate forensic investigations if attackers use spoofing to hide their tracks. Overall, the impact is contained but significant for environments with weak physical controls or legacy system dependencies.

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. Disable or restrict use of removable media and external devices that could be used to exploit the vulnerability. 4. Implement endpoint detection and response (EDR) solutions to monitor for suspicious file system activity or spoofing attempts. 5. Conduct regular audits of physical device security, especially in shared or public environments. 6. Educate staff on the risks of physical tampering and encourage reporting of suspicious device behavior. 7. Maintain up-to-date backups and ensure integrity checks to detect unauthorized changes. 8. Monitor vendor advisories for patches or updates addressing this vulnerability and apply them promptly once available.