A flaw was found in Keycloak. This vulnerability allows anyone to register a new security device or key when there is not a device already registered for any user by using the WebAuthn password-less login flow.
https://issues.redhat.com/browse/KEYCLOAK-18500
https://github.com/keycloak/keycloak/pull/8203
https://github.com/keycloak/keycloak/commit/65480cb5a11630909c086f79d396004499fbd1e4