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Authy got hacked, and 33 million user phone numbers were stolen
(appleinsider.com)
This is a most excellent place for technology news and articles.
They absolutely gained unauthorized access to the data. Their access was not intended or sanctioned. If it was intended to be public and accessible like it was, this wouldn't be a story and they wouldn't have locked down the access.
But by the guy's definition, they also used a loophole to extract sensitive information, so it it also an exploit.