Why is my Fraction object returns bad values as new object in C++?

Question

I'm trying to make Fraction object and overload a few operators. The problem is at the moment I want to multiply two fractions, because it returns fraction with numerator equals to -858993460 as well as denominator.

Fraction::Fraction(int numerator, int denominator)
{
    if (denominator == 0)
        throw std::overflow_error("Denominator can't be 0");
    else {
        this->numerator = numerator;
        this->denominator = denominator;

        if (this->numerator < 0 && this->denominator < 0) {
            this->numerator = -this->numerator;
            this->denominator = -this->denominator;
        }
    }
}

Fraction::Fraction(const Fraction & scndFraction)
{
    if (scndFraction.denominator == 0)
        throw std::overflow_error("Denominator can't be 0");
    else {
        this->numerator = scndFraction.numerator;
        this->denominator = scndFraction.denominator;
    }
}

Fraction & Fraction::operator*(const Fraction& scndFraction)
{
    // TODO: Sem vložte návratový příkaz.
    Fraction newFraction(this->numerator*scndFraction.getNumerator(),
        this->denominator*scndFraction.getDenominator());

    return newFraction;
}

And main.cpp

#include "Fraction.h"
#include <Windows.h>

int main() {
    //HANDLE hnd = GetStdHandle(STD_OUTPUT_HANDLE);
    //SetConsoleTextAttribute(hnd, FOREGROUND_BLUE);

    Fraction first(1, 2);
    std::cout << first.getFraction() << std::endl;

    Fraction second(1, 2);
    std::cout << second.getFraction() << std::endl;

    Fraction third = second * first;
    std::cout << third.getFraction() << std::endl;

    getchar();

    return 0;
}