Google Calendar app has been downloaded more than a billion times from the Play Store. Security researchers warned that threat actors are exploiting the popularity of both in order to target users with a credential-stealing attack. Using a single Google dork (advance search query), I am able to list down all the public google calendar or users who all have set their calendar as public. I found dozens of calendars which are indexed by googles search engines, revealing or disclosing several sensitive information. I have found more than 200+ such calendar which is marked as public and indexed by Google search engine.”]
Source: https://logicbomb.medium.com/ok-google-please-reveal-everyones-public-calendar-27523206f9ac