A flaw was found in the OIDC implementation of Keycloak, specifically within the Device Authorization Grant flow. This component allows devices with limited input capabilities to obtain security tokens. The issue occurs because the flow fails to check the minimum authentication level required by a client configuration. This allows an attacker who has stolen a users password to bypass mandatory multi-factor authentication and gain unauthorized access to the Keycloak Admin REST API.
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.