Impact Pageflow has a membership edit feature which allows users to edit the roles of user memberships associated with an account that they have the "manager" role to (including their own). While the "Entity" dropdown select field is greyed out in the UI, an attacker can use tools which allow sending arbitrary HTTP request to craft a request to the "/admin/users/{user_id}/memberships/{membership_id}" endpoint containing an additional "membership[entity_id]" parameter. This parameter is honored when the membership is updated, allowing an attacker to update the membership object associated with their own account (with "manager" role) to be associated with a different attacker-chosen account instead. Since "account_id"s are enumerable, an attacker can compromise all accounts present on the platform. Mitigation Upgrade to version 15.7.1 or 14.5.2 of the "pageflow" gem. For more information If you have any questions or comments about this advisory email us at info(at)codevise.de Credits "Positive Security" (https://positive.security/)