oauth misconfigration lead to account takeover

How it was found

Summary:

misconfigration in aouth 2.0 login with google account in "accounts.reddit.com"

Impact:

misconfigration leads to account takeover

Steps To Reproduce:

1. go to "https://accounts.reddit.com/".
2. and login with your google account.
3. after login, logout from your account.
4. after logout go to "https://accounts.reddit.com/account/register/" and register with email you signed in before in google account oauth.
5. as like you see it's created a new account

• [attachment / reference]

Impact

attacker can login with any user's email thats lead to account takeover