A flaw was found in Keycloak. A remote, unauthenticated attacker can exploit this vulnerability by sending specially crafted SOAP requests to the SAML ECP (Security Assertion Markup Language Enhanced Client or Proxy) endpoint with varying client IDs. By observing distinct faultstrings in the responses, the attacker can determine the client's protocol type, leading to information disclosure.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.