Org.keycloak.forms.login: keycloak: keycloak: arbitrary code execution via stored cross-site scripting (xss) in organization selection login page

A flaw was found in Keycloak, specifically in the organization selection login page. A remote attacker with `manage-realm` or `manage-organizations` administrative privileges can exploit a Stored Cross-Site Scripting (XSS) vulnerability. This flaw occurs because the `organization.alias` is placed into an inline JavaScript `onclick` handler, allowing a crafted JavaScript payload to execute in a user's browser when they view the login page. Successful exploitation enables arbitrary JavaScript execution, potentially leading to session theft, unauthorized account actions, or further attacks against users of the affected realm.