“I know America’s voting machines are vulnerable, because my colleagues and I have hacked them repeatedly. As part of a decade of research, studying the technology that operates elections and learning how to make it stronger.
“We’ve created a tax that can spread from machine to machine like a computer virus, and silently changed election outcomes. We’ve studied touch screen and optical scam systems and in every single case we found ways for attackers to sabotage machines and to steal votes.”
Snowden has also shared in 2016 how easy it is to HACK into a US voting machine with a £24 memory card: https://humansarefree.com/2020/11/edward-snowden-computer-science-prof-explain-how-easily-voting-machines-can-be-hacked.html