Airbnb – Web to App Phone Notification IDOR to view Everyone’s Airbnb Messages

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Airbnb recently created a new feature called Experiences which allows you to book things to do rather than places to stay. With the new code changes that came along with Experiences, we discovered a page that allowed you to send yourself a text message with a link to download the Airbnb app. This sent a POST request to an API endpoint we had never seen before. Using the JS Parser tool we built we discovered another API call associated with it. We found that these API calls were vulnerable to Insecure Direct Object Reference (IDOR) and allowed you to view all messages on Airbnb by ID.

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