A flaw was found in Keycloak, where it does not correctly validate its client step-up authentication in org.keycloak.authentication. This flaw allows a remote user authenticated with a password to register a false second authentication factor along with an existing one and bypass authentication.
https://bugzilla.redhat.com/show_bug.cgi?id=2221760
https://access.redhat.com/security/cve/CVE-2023-3597