CVE-2023-6291 is an open redirect vulnerability identified in the redirect_uri validation logic of Red Hat's build of Keycloak version 22. Keycloak is an open-source identity and access management solution widely used for single sign-on and authentication services. The vulnerability allows an attacker to bypass the intended restrictions on redirect URIs, which are supposed to limit redirection to explicitly allowed hosts. By exploiting this flaw, an attacker can craft a malicious URL that redirects users to an attacker-controlled site. This redirection can be leveraged to steal access tokens during the OAuth2/OpenID Connect authentication flows. Access tokens are critical credentials that grant access to protected resources and services. If stolen, attackers can impersonate legitimate users, potentially gaining unauthorized access to sensitive systems and data. The vulnerability has a CVSS 3.1 score of 7.1, indicating high severity, with an attack vector of network, low attack complexity, no privileges required, but requiring user interaction. The scope is changed, meaning the vulnerability affects components beyond the initially targeted scope. The impact affects confidentiality, integrity, and availability, as unauthorized access can lead to data breaches and service disruption. No public exploits are currently known, but the risk remains significant due to the nature of the vulnerability and the critical role of Keycloak in identity management.

For European organizations, the impact of CVE-2023-6291 can be substantial, especially for those relying on Red Hat's Keycloak 22 for authentication and authorization services. Successful exploitation can lead to unauthorized access to corporate applications, sensitive personal data, and critical infrastructure. This can result in data breaches, compliance violations (e.g., GDPR), reputational damage, and potential financial losses. The ability to impersonate users undermines trust in identity systems and can facilitate further lateral movement within networks. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitivity of the data and services protected by Keycloak. The requirement for user interaction means phishing or social engineering campaigns could be used to trigger the exploit, increasing the attack surface. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits over time.

1. Apply official patches or updates from Red Hat as soon as they become available to address the redirect_uri validation flaw. 2. Until patches are applied, implement strict validation and whitelisting of redirect URIs at the application or proxy level to prevent redirection to untrusted domains. 3. Employ multi-factor authentication (MFA) to reduce the risk of token misuse even if tokens are stolen. 4. Monitor authentication logs and redirect requests for unusual patterns or anomalies indicative of exploitation attempts. 5. Educate users about phishing risks and suspicious links to reduce the likelihood of user interaction with malicious URLs. 6. Consider deploying web application firewalls (WAF) with rules to detect and block open redirect attempts targeting Keycloak endpoints. 7. Review and tighten OAuth2/OpenID Connect client configurations to minimize exposure. 8. Conduct regular security assessments and penetration testing focusing on identity management components.