 The researcher also tells TechCrunch he couldn't make all the lights turn green due to other tech that confounded him. But even still, the traffic signals were susceptible to hacking. It's unknown how many at-risk traffic signals sold to multiple municipalities could be at risk or whether or not they're still in service or have since been patched. But now is a good time to remind you that if you encounter a malfunctioning traffic light, treat it like a multi-way stop.