Keystone is an open source headless CMS for Node.js — built with GraphQL and React. When ui.isAccessAllowed is set as undefined, the adminMeta GraphQL query is publicly accessible (no session required). This is different to the behaviour of the default AdminUI middleware, which by default will only be publicly accessible (no session required) if a session strategy is not defined. This vulnerability does not affect developers using the @keystone-6/auth package, or any users that have written their own ui.isAccessAllowed (that is to say, isAccessAllowed is not undefined). This vulnerability does affect users who believed that their session strategy will, by default, enforce that adminMeta is inaccessible by the public in accordance with that strategy; akin to the behaviour of the AdminUI middleware. This vulnerability has been patched in @keystone-6/core version 5.5.1. Users are advised to upgrade. Users unable to upgrade may opt to write their own isAccessAllowed functionality to work-around this vulnerability.