Likely none, but nation-states can also manipulate traditional voting with enough effort.
(classic spycraft, blackmailing of key persons, intercept mailvoting, etc.)
Nothing is 100% secure.
So the question is, is it good enough?
They said they took great effort to verificate the voting and detect manipulation. I cannot confirm or verify it, but since it is open, I could. That is a great step forward, compared to the closed black boxes, e-voting systems I have heard of before.
