Kimai is an open-source time tracking application. Prior to 2.57.0, GET or POST requests to /en/admin/project/{id}/rate/{rate}, /en/admin/customer/{id}/rate/{rate}, and /en/admin/activity/{id}/rate/{rate} independently resolve the authorized parent identifier and the attacker-selected child rate identifier without confirming that the ProjectRate, CustomerRate, or ActivityRate belongs to that parent. An authenticated user who can edit one parent object can pair it with a rate record from an unauthorized project, customer, or activity and persist changes to billing configuration in kimai2_projects_rates, kimai2_customers_rates, or kimai2_activities_rates. This issue is fixed in version 2.57.0.