A flaw was found in the X.509 client-certificate authenticator of Keycloak, a solution for identity and access management. The issue occurs when the server is configured to check certificate revocation using CRL Distribution Points or OCSP. An attacker can provide a specially crafted certificate that points to a malicious server, causing Keycloak to make unauthorized outbound requests to internal or external endpoints before the certificate is fully validated. This can lead to a blind server-side request forgery (SSRF) attack.
Weakness
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.