A new report from University of Michigan researchers finds that traffic light hacking is a real possibility.

"[The] critical nature of traffic infrastructure requires that it be secure against computer-based attacks, but this is not always the case," the report said.

The researchers, paired with a local Michigan road agency, uncovered three major weaknesses in the traffic infrastructure. All three fell under the category of "inadequate security". Lack of encryption and secure authentication was the main issue, which could lead to a denial of service attack, traffic congestion, and light control, among other possibilities.

"With the appropriate hardware and a little effort, an adversary can reconfigure a traffic controller to suit [their] needs," the paper said.

More than 40 states currently use similar wireless systems.