The paper that this CBC article is based on: https://link.springer.com/chapter/10.1007/978-3-032-05036-6_...

There's a great and very detailed report written after the 2018 municipal elections that outlines some security issues with online voting in practice:

https://whisperlab.org/ontario-online.pdf

I'll also shamelessly plug my thesis which, among other things, describes an interesting ballot secrecy vulnerability in one online voting system that allows a passive network observer to determine who someone voted for:

https://uwo.scholaris.ca/server/api/core/bitstreams/4e74d806...