For many safety-critical systems, implementing modern cybersecurity protection mechanisms is hindered by legacy design and high re-certification costs. Since such systems are typically designed to be highly reliable, they usually contain a large number of redundant components used to achieve fault tolerance. In this paper, we discuss challenges in utilising redundancy inherently present in the architectures of safety-critical systems to enhance system cybersecurity protection. We consider classic redundant architectures and analyse their ability to protect against cyberattacks. By evaluating the likelihood of a successful cyberattack on a redundant architecture under different implementation conditions, we conclude that redundancy in combination with diversity has better potential to be utilised for cybersecurity protection.