CVE-2025-12789 is an Open Redirect vulnerability identified in Red Hat Single Sign-On (RH-SSO) version 7, specifically affecting the logout process that utilizes the OpenID Connect protocol. The vulnerability arises because the redirect_uri parameter, which dictates the URL to which users are redirected after logout, is not properly validated. This improper validation allows an attacker to craft malicious logout URLs that redirect users to arbitrary, potentially malicious external websites. Such open redirects can be leveraged in phishing campaigns or social engineering attacks to deceive users into trusting and interacting with harmful sites, potentially leading to credential theft or malware infection. The vulnerability has a CVSS 3.1 base score of 6.1, reflecting a medium severity level, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and requiring user interaction (UI:R). The scope is changed (S:C), indicating that exploitation can affect resources beyond the vulnerable component. The impact affects confidentiality and integrity to a limited extent but does not affect availability. No known exploits are currently reported in the wild, and no official patches have been linked yet, though Red Hat is the assigner and likely to release fixes. The vulnerability is particularly relevant for organizations that rely on RH-SSO 7 for authentication and session management, as it undermines trust in the logout process and can facilitate targeted attacks.

For European organizations, this vulnerability poses a risk primarily to user trust and security posture. Since RH-SSO is widely used in enterprise environments for centralized authentication, an attacker exploiting this flaw could redirect users to malicious sites after logout, potentially leading to credential phishing or session hijacking attempts. This can compromise user confidentiality and integrity of authentication workflows. Sectors such as finance, government, healthcare, and critical infrastructure that rely heavily on secure single sign-on solutions are particularly vulnerable. The medium severity rating reflects that while the vulnerability does not directly compromise system availability or require authentication, the potential for social engineering and credential theft can have significant downstream impacts. Additionally, the scope change in the CVSS vector suggests that the vulnerability could affect multiple components or systems relying on RH-SSO, increasing the potential impact. The absence of known exploits in the wild reduces immediate risk but does not eliminate the need for proactive mitigation, especially given the strategic importance of secure authentication in European digital services.

European organizations should implement the following specific mitigations: 1) Monitor Red Hat advisories closely and apply patches or updates for RH-SSO 7 as soon as they become available to address CVE-2025-12789. 2) In the interim, configure RH-SSO to enforce strict validation of redirect_uri parameters, allowing only pre-approved, whitelisted URLs to prevent arbitrary redirects. 3) Employ web application firewalls (WAFs) with rules designed to detect and block suspicious redirect patterns related to logout URLs. 4) Educate end-users and administrators about the risks of open redirects and encourage vigilance when clicking logout links or URLs received via email or other channels. 5) Review and audit all integrations and customizations involving RH-SSO logout flows to ensure they do not introduce additional redirect vulnerabilities. 6) Implement multi-factor authentication (MFA) to reduce the impact of credential theft resulting from phishing attacks leveraging this vulnerability. 7) Conduct regular security assessments and penetration testing focusing on authentication and logout mechanisms to detect similar issues proactively.