CVE-2025-8069 is a high-severity vulnerability affecting the AWS Client VPN client on Windows platforms, specifically versions 4.1.0 and 5.0.0. The vulnerability arises due to incorrect default permissions during the installation process. When the AWS Client VPN client is installed on Windows devices, the installer references the directory C:\usr\local\windows-x86_64-openssl-localbuild\ssl to retrieve the OpenSSL configuration file. This directory is accessible to non-administrative users, allowing them to place or modify the OpenSSL configuration file arbitrarily. If an administrative user subsequently initiates the installation process, the maliciously crafted configuration file can execute arbitrary code with root-level (system) privileges. This privilege escalation vector exploits the improper permission settings on the configuration directory and the trust the installer places on the OpenSSL configuration file. Notably, this vulnerability is limited to Windows environments and does not affect Linux or macOS versions of the AWS Client VPN client. The CVSS 4.0 base score of 7.3 reflects the vulnerability's high impact, considering it requires local access with low complexity but does not require user interaction. The attacker must have some level of privileges (non-admin) to place the malicious file, and an admin must run the installer to trigger the exploit. There are no known exploits in the wild as of the publication date, and AWS recommends discontinuing new installations of affected versions prior to upgrading to version 5.2.2 or later where the issue is presumably fixed. This vulnerability is categorized under CWE-276 (Incorrect Default Permissions), highlighting the root cause as improper access control on critical installation files.

For European organizations, this vulnerability poses a significant risk primarily in environments where AWS Client VPN is deployed on Windows endpoints. Successful exploitation leads to local privilege escalation, allowing attackers with limited user rights to gain administrative control over the affected system. This can result in unauthorized access to sensitive corporate networks, data exfiltration, lateral movement within the network, and potential deployment of persistent malware or ransomware. Given that AWS Client VPN is often used to securely connect remote or hybrid workforce endpoints to corporate resources, compromised VPN clients can undermine the security perimeter and facilitate further attacks. The impact is particularly critical for organizations handling sensitive personal data under GDPR, as unauthorized access could lead to data breaches with legal and financial consequences. Additionally, the vulnerability could disrupt business continuity if attackers leverage elevated privileges to disable security controls or disrupt VPN connectivity. Since the vulnerability requires local access and administrative user action to trigger, the risk is elevated in environments where endpoint security hygiene is weak, or where users frequently install or update software with administrative privileges.

European organizations should immediately halt any new installations of AWS Client VPN on Windows versions 4.1.0 and 5.0.0. Existing installations should be audited to identify affected versions and upgraded to AWS Client VPN version 5.2.2 or later, where the vulnerability is addressed. Organizations should enforce the principle of least privilege by restricting local user permissions to prevent unauthorized file modifications in installation directories. Endpoint security solutions should monitor and alert on suspicious file changes in directories related to VPN client installations. Additionally, administrative users should be trained to avoid running installers or updates from untrusted sources and to verify the integrity of installation files. Implementing application whitelisting can prevent execution of unauthorized code during installation. Network segmentation and strict access controls can limit the impact of compromised endpoints. Finally, organizations should maintain up-to-date asset inventories and patch management processes to rapidly identify and remediate vulnerable clients.