We establish a moderate deviation principle for the maximum likelihood es-timator of the four parameters of a geometrically ergodic Heston process. We also obtain moderate deviations for the maximum likelihood estimator of the couple of dimensional and drift parameters of a generalized squared radial Ornstein-Uhlenbeck process. We restrict ourselves to the most tractable case where the dimensional parameter satisfies a > 2 and the drift coefficient is such that b < 0. In contrast to the previous literature, parameters are estimated simultaneously.