A vulnerability in the expo.io framework allows an attacker to take over accounts and steal credentials on an application/website that configured the "Expo AuthSession Redirect Proxy" for social sign-in. This can be achieved once a victim clicks a malicious link. The link itself may be sent to the victim in various ways (including email, text message, an attacker-controlled website, etc).
The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.