CVE-2025-12789 identifies an Open Redirect vulnerability in Red Hat Single Sign-On (RH-SSO) version 7, specifically during the logout process that uses the OpenID Connect protocol. The vulnerability stems from improper validation of the redirect_uri parameter, which is intended to specify the URL to which users are redirected after logout. Because the parameter is not properly sanitized or restricted, an attacker can craft a malicious logout URL that redirects users to an untrusted external site. This can be exploited by tricking users into clicking such URLs, potentially enabling phishing attacks, credential harvesting, or other social engineering exploits by leveraging the trust users place in the legitimate RH-SSO domain. The vulnerability is exploitable remotely over the network without requiring authentication, but it does require user interaction (clicking the malicious link). The CVSS v3.1 score of 6.1 reflects medium severity, with confidentiality and integrity impacts rated as low, and no impact on availability. The scope is changed (S:C) because the vulnerability affects resources beyond the vulnerable component. No known public exploits have been reported yet, and no patches or mitigations have been linked at the time of publication. Given RH-SSO's role in centralized authentication and single sign-on for enterprise applications, this vulnerability could undermine user trust and facilitate further attacks if combined with phishing or session fixation techniques.

For European organizations, the impact of CVE-2025-12789 can be significant in environments where Red Hat Single Sign-On 7 is deployed to manage user authentication across multiple applications. An attacker exploiting this vulnerability could redirect users to malicious websites during logout, potentially leading to phishing attacks that compromise user credentials or session tokens. This undermines the integrity of the authentication process and could facilitate unauthorized access to sensitive systems. While the vulnerability does not directly compromise availability, the loss of user trust and potential data breaches could have regulatory and reputational consequences, especially under GDPR requirements. Organizations in sectors such as finance, government, healthcare, and critical infrastructure that rely heavily on RH-SSO for identity management are at higher risk. The medium severity rating indicates a moderate risk level, but the ease of exploitation via crafted URLs and the widespread use of RH-SSO in enterprise environments elevate the threat profile. The lack of authentication requirement means attackers can target any user, increasing the attack surface.

To mitigate CVE-2025-12789, organizations should implement strict validation and whitelisting of the redirect_uri parameter in the logout flow to ensure only trusted URLs within the organization's domain or approved endpoints are allowed. This can be enforced by configuring RH-SSO settings to restrict redirect targets and by applying input sanitization to prevent injection of arbitrary URLs. Monitoring and logging logout requests for unusual redirect patterns can help detect exploitation attempts. User education on the risks of clicking unexpected logout links and phishing awareness training are also important. Organizations should track Red Hat security advisories closely and apply patches or updates as soon as they become available. Where possible, deploying web application firewalls (WAFs) with rules to detect and block open redirect attempts can provide an additional layer of defense. Finally, integrating multi-factor authentication (MFA) can reduce the impact of credential theft resulting from phishing attacks leveraging this vulnerability.