Okay kiddo, so the ROCA vulnerability is about keys. Keys are like secret codes that computers use to keep things safe. Just like you might have a secret code to get into your treehouse, computers use keys to protect important things, like your mom's password or your dad's bank account info.
Now, sometimes people make mistakes when they create keys. It's kind of like if you accidentally told your friend your treehouse code and they went inside without you knowing. That would not be good!
Well, the ROCA vulnerability is a mistake that some people made when creating keys. It means that bad guys could figure out what the keys are, even if they're supposed to be secret. That's like if somebody figured out the secret code to your treehouse and started messing with your toys when you're not there!
So, grown-ups who work with computers are trying to fix the ROCA vulnerability so that bad guys can't get into things that are supposed to be secret. Just like your parents might change the code to your treehouse to keep your toys safe.