Today, FPGAs are essential components in many computing systems. Compared to ASICs, they offer reconfigurability, lower design costs, reduced system complexity, and decreased time to market, while achieving performance gains due to abundant hardware parallelism. With conventional CPUs, FPGAs are deployed in various critical systems, such as wireless base stations, satellites, radars, electronic warfare platforms, and data centers. Both FPGAs and CPUs have security vulnerabilities; integrating them together presents new attack opportunities on both sides. In this project, we investigate the attacks made possible by closely integrating FPGAs with CPUs in heterogeneous computing platforms. We look at known attacks on CPUs (e.g., side channels, memory corruption), FPGAs (hardware Trojans, side channels, and most recently discovered fault-attacks), and their synergies. Additionally, we investigate the potential for new attacks specific to these heterogeneous platforms. Understanding the mechanisms behind these threats and what they mean for safety-critical applications enables us to design strong and reliable defenses, critical for safe and secure heterogeneous computing.