Exception thrown at 0x793F3729 (vcruntime140d.dll) in filePath.exe: 0xC0000005: Access violation writing location 0xCDCDCDCD

I'm attempting to implement a linked list as a stack so I created on a custom class for it in C++. Below is what I used to push the temp1 variable into the stack. My current issue is when I push into the stack, it throws an exception.

cityNode temp1(dest, cost + dataVector[index].cost, time + dataVector[index].time);
stack->pushCity(temp1);

This is the node.

class cityNode {
    public:
        string name;                        // City name
        double totalCost;                   // Total cost of the flight
        int totalTime;                      // Total time of the flight
        cityNode* destCity;                 // Pointer to the next destionation city

        cityNode(string cityName, double cityCost, int cityTime) {
            name = cityName;
            totalCost = cityCost;
            totalTime = cityTime;
            destCity = nullptr;
        }
};

Below is my code. The exception is currently thrown when it reaches the newCity->totalCost = cityNode.totalCost; part of the code.

class CityStack {
    public:
        class cityNode* top = NULL;
        void pushCity(cityNode cityNode) {
            class cityNode* newCity = (class cityNode*) malloc(sizeof(class cityNode));
            newCity->name = cityNode.name;
            newCity->totalCost = cityNode.totalCost;            // Exception Thrown
            newCity->totalTime = cityNode.totalTime;
            newCity->destCity = top;
            top = newCity;
        }

        void popCity() {
            if (top == NULL) {
                cout << "Stack Underflow" << endl;
            }
            else {
                top = top->destCity;
            }
        }

        bool emptyCity() {
            if (top == NULL)
                return true;
            else
                return false;
        }

        void reverseCity() {
            cityNode *prev, *cur, *succ;
            cur = prev = top;
            //cur = cur->destCity;
            while (cur != NULL) {
                cityNode *temp = cur->destCity;
                delete cur;
                cur = temp;
            }

            //prev->destCity = NULL;
            while (prev != NULL) {
                cityNode *temp = prev->destCity;
                delete prev;
                prev = temp;
            }

            while (cur != NULL) {
                succ = cur->destCity;
                cur->destCity = prev;
                prev = cur;
                cur = succ;
            }
            top = prev;
        }

        void displayCities() {
            cityNode *stack = top;
            while (stack != NULL) {
                cout << stack->name << " ";
                stack = stack->destCity;
            }
            cout << endl;
        }

        cityNode* getCityNode() {
            return top;
        }
};

Don't use malloc in a C++ program (unless you really know what you are doing) because it doesn't call the constructors for the objects you are creating.

Replace this

class cityNode* newCity = (class cityNode*) malloc(sizeof(class cityNode));

with this

cityNode* newCity = new cityNode;