In a dispersed storage network where slices of secure user data are stored on geographically separated storage units (44), a managing unit (18) connected to the network (20) may seek to broadcast and update secure access control list information across the network (20). Upon a target device (e.g., devices 12, 14, 16, 18, or 44) receiving the broadcast the target device creates and sends an access control list change notification message to all other system devices that should have received the same broadcast if the broadcast is a valid request to update access control list information. The target device waits for responses from the other system devices to validate that the broadcast has been properly sent to a threshold number of other system devices before taking action to operationally change local data in accordance with the broadcast.