The quadratic Gaussian CEO problem is studied when the agents are under Byzantine attack. That is, an unknown subset of agents is controlled by an adversary that attempts to damage the quality of the estimate at the Central Estimation Officer, or CEO. Inner and outer bounds are presented for the achievable rate region as a function of the fraction of adversarial agents. The inner bound is derived from a generalization of the Berger-Tung quantize-and-bin strategy, which has been shown to be tight in the non-Byzantine case. The outer bound has similarities to the Singleton bound in that the traitorous agents must be prevented from allowing two sources to result in the same transmitted codewords if their values are too far apart for the distortion constraint to be satisfied with a single estimate. The inner and outer bounds on the rate regions are used to find bounds on the asym ptotic proportionality constant in the limit of a large number of agents and high sum-rate. These bounds on the proportionality constant differ at most by a factor of 4.