Whoa there, no it's totally fine. It has great error and collision detection, is very tolerant of noise, has priority for realtime baked in, all the controllers do rudimentary and effective protections against failed controller, and the entire notion of some controller sending something a few are interested in and a controller interested in the same message that a number of different controllers may send is central tenant to the operation.

The mistake is making it accessible over a cellular network. This was not careful air gapping. The OEMs will learn a lot from this. They had protections but they were not strong enough. There will be protections that are harder in the future thanks to this.

CAN is really quite good and in fact is used at times in industrial automation as well as automotive where it shines.