CVE-2025-50055 is a cross-site scripting (XSS) vulnerability identified in the SAML Authentication module of OpenVPN Access Server versions 2.14.0 through 2.14.3. The vulnerability stems from improper input neutralization (CWE-79) during web page generation, specifically involving the RelayState parameter used in SAML authentication flows. The RelayState parameter is intended to maintain state information between the identity provider (IdP) and the service provider (SP) during SAML exchanges. However, in this case, a malicious or compromised remote SAML Assertion Consumer Service (ACS) endpoint server can inject arbitrary HTML or JavaScript code via the RelayState parameter. When a user accesses the OpenVPN Access Server's web interface, this injected script executes in the user's browser context, potentially leading to session hijacking, credential theft, or other malicious actions. The vulnerability requires that the attacker controls or manipulates the remote ACS endpoint, which is a trusted entity in the SAML flow, making exploitation feasible in environments where ACS endpoints are not strictly controlled or validated. No CVSS score has been assigned yet, and no known exploits have been reported in the wild as of the publication date. The vulnerability was reserved in June 2025 and published in October 2025. Since OpenVPN Access Server is widely used for secure remote access, especially in enterprise and critical infrastructure environments, this vulnerability could have significant security implications if exploited. The lack of a patch link suggests that a fix may still be pending or in development, emphasizing the need for immediate attention from administrators. The vulnerability affects confidentiality and integrity by enabling script execution that can compromise user sessions and data. The scope is limited to environments using the affected OpenVPN versions with SAML authentication enabled. Exploitation does not require user interaction beyond accessing the affected web interface, but it does require a malicious or compromised ACS endpoint, which may limit the attack surface. Overall, this vulnerability highlights the importance of input validation and strict trust boundaries in federated authentication systems like SAML.

For European organizations, the impact of CVE-2025-50055 can be significant, particularly for those relying on OpenVPN Access Server with SAML authentication for secure remote access. Successful exploitation could allow attackers to execute arbitrary scripts in users' browsers, leading to session hijacking, credential theft, or unauthorized actions within the VPN portal. This compromises confidentiality and integrity of sensitive corporate data and user credentials. Given the widespread use of OpenVPN in European enterprises, government agencies, and critical infrastructure sectors, the vulnerability could facilitate lateral movement or persistent access if attackers leverage stolen credentials. The risk is heightened in environments where multiple ACS endpoints are configured or where endpoint security is lax, increasing the likelihood of malicious RelayState injection. Additionally, the vulnerability could undermine trust in federated authentication mechanisms, potentially disrupting secure access workflows. Although no availability impact is directly indicated, the indirect effects of compromised sessions could lead to operational disruptions or increased incident response costs. The absence of known exploits suggests a window for proactive mitigation, but the potential impact warrants urgent attention.

European organizations should take the following specific actions to mitigate CVE-2025-50055: 1) Immediately audit all configured SAML Assertion Consumer Service (ACS) endpoints to ensure they are trusted and secure; remove or disable any untrusted or unnecessary endpoints. 2) Implement strict input validation and sanitization on the RelayState parameter within the OpenVPN Access Server configuration or through web application firewalls (WAFs) to block malicious script injection. 3) Monitor OpenVPN vendor advisories closely and apply patches or updates as soon as they become available, prioritizing upgrades beyond version 2.14.3. 4) Restrict access to the OpenVPN Access Server management interface to trusted networks and users to reduce exposure. 5) Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in the web interface context. 6) Conduct user awareness training to recognize suspicious authentication behaviors or unexpected redirects during SAML login flows. 7) Consider implementing multi-factor authentication (MFA) at the VPN access level to mitigate risks from stolen credentials. 8) Regularly review and update SAML configurations to follow best practices, including endpoint validation and metadata integrity checks. These targeted measures go beyond generic advice by focusing on the specific attack vector and the federated authentication context.