Seemingly random crash originating in QtWebEngineCore::AuthenticationDialogController::url

I don't have a repro but have stack traces from two crashes reported by two different users (Windows 10 Enterprise and Windows 10 Pro). Our gui application is built using Qt 5.9.2 (if it matters I can provide the config line that is used to build the libraries). My hope is that someone who is familiar with that part of the Qt could point me to a next step that could help us with finding the cause. In the stack traces fmeworkbench is our gui application.