Traccar is an open source GPS tracking system. Prior to 6.14.0, an authenticated user with permission to manage groups and request reports can create a cyclic group-parent hierarchy and request a trips or stops report for a device in that hierarchy. org.traccar.api.resource.GroupResource permits the parent cycle, while org.traccar.helper.model.AttributeUtil.lookup follows group parents without cycle detection, a visited set, or a depth limit. The storage-backed lookup reached through TripsConfig. and ReportUtils.slowTripsAndStops never terminates, pins a Jetty worker at high CPU after the client disconnects, and can exhaust the web/API worker pool when requests are repeated. The position-ingestion cache-backed path is not part of the confirmed affected scope. This issue is fixed in 6.14.0.