CVE-2025-50055 is a cross-site scripting (XSS) vulnerability classified under CWE-79 found in the SAML Authentication module of OpenVPN Access Server versions 2.14.0 through 2.14.3. The vulnerability arises from improper neutralization of input during web page generation, specifically through the RelayState parameter used in SAML authentication flows. The RelayState parameter is intended to maintain state information between the identity provider and the service provider during SAML assertions. However, in this case, a remote SAML Assertion Consumer Service (ACS) endpoint server, which is configured within the OpenVPN Access Server, can inject arbitrary HTML or JavaScript code via this parameter. Because the injected script executes in the context of the OpenVPN Access Server's web interface, it can lead to session hijacking, credential theft, or other malicious actions impacting confidentiality and integrity of user sessions. The vulnerability has a CVSS 3.1 base score of 6.4, indicating a medium severity level. The attack vector is network-based (AV:N), requires low attack complexity (AC:L), and low privileges (PR:L), but no user interaction (UI:N). The scope is changed (S:C), meaning the vulnerability affects resources beyond the initially vulnerable component. There are no known public exploits or patches available at the time of disclosure, increasing the urgency for organizations to implement mitigations. This vulnerability is particularly critical in environments where OpenVPN Access Server is used with SAML for federated authentication, as it undermines the trust model of the authentication process.

For European organizations, this vulnerability poses a risk to the confidentiality and integrity of remote access sessions managed via OpenVPN Access Server with SAML authentication enabled. Exploitation could allow attackers to execute malicious scripts in the context of the administrative or user web interface, potentially leading to session hijacking, theft of authentication tokens, or unauthorized actions within the VPN management console. This could result in unauthorized access to internal networks, data exfiltration, or lateral movement within enterprise environments. Given the widespread use of OpenVPN in European enterprises, government agencies, and critical infrastructure sectors, the impact could be significant, especially where SAML-based single sign-on is integrated for user authentication. The vulnerability does not directly affect availability but can indirectly disrupt operations if attackers gain control over VPN access. The absence of known exploits reduces immediate risk but does not eliminate the threat, as attackers may develop exploits once the vulnerability details are public. Organizations relying on OpenVPN Access Server for secure remote access should consider this vulnerability a medium risk that requires timely attention to prevent potential compromise.

1. Immediately review and restrict the configuration of SAML Assertion Consumer Service (ACS) endpoints to only trusted and verified sources to minimize the risk of malicious RelayState injection. 2. Implement strict input validation and output encoding on the RelayState parameter within the OpenVPN Access Server web interface to neutralize potentially malicious scripts. 3. Monitor OpenVPN Access Server logs for unusual or unexpected RelayState parameter values that could indicate exploitation attempts. 4. Where possible, disable SAML authentication temporarily or switch to alternative authentication methods until a patch is released. 5. Employ web application firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the RelayState parameter. 6. Keep OpenVPN Access Server updated and subscribe to vendor advisories for prompt application of security patches once available. 7. Educate administrators and users about the risks of XSS and encourage the use of multi-factor authentication to reduce the impact of potential session hijacking. 8. Conduct regular security assessments and penetration testing focusing on the VPN infrastructure and authentication mechanisms to identify and remediate similar vulnerabilities proactively.