Sounds like you have found some initial implementation problems that you have potential solutions for. The most important thing would be how secure is your appliance and how secure things are for when someone does get shell access.
Is all input validated and all output sanitized? Is the software continuously kept updated? Are you keeping up with regulations and security protocols required by the countries that your appliance is used in? Are you offering enterprise support contracts to pay for the added work of maintenance per customer?
Is all input validated and all output sanitized? Is the software continuously kept updated? Are you keeping up with regulations and security protocols required by the countries that your appliance is used in? Are you offering enterprise support contracts to pay for the added work of maintenance per customer?