GPUs effectively have general-purpose compute now and they can DMA bytes into and out of system memory. At a basic level, sneaky on-GPU code run by an attacker

GPUs effectively have general-purpose compute now and they can DMA bytes into and out of system memory. At a basic level, sneaky on-GPU code run by an attacker could grab pixels off your screen (text from your emails, etc), but it's also possible for the GPU-based attack code to harvest data from system memory or even mess with data in order to attack a process running on the CPU.