I don't know Canadian law, just for fun this is my understanding of it under US laws which are likely similar although Canada usually has more consumer protections.
You generally can't waive negligence. Those waivers can be useful for things like a trampoline park - someone lands on their ankle wrong and injurs it, the waiver deals with assumption of the risk - landing incorrectly is a reasonable risk due to the nature of the event. However if a net was missing and you hit the concrete floor - that would be under negligence of the premises owner.
My guess (not a lawyer just guessing) is that if they followed all best practices and someone bruteforced an RSA 2048 key which is currently understood to not be (reasonably) possible - that might be covered? However if they left a S3 bucket open without a password, that would be under negligence?