Python Social Auth is a social authentication/registration mechanism. In versions prior to 5.6.0, upon authentication, the user could be associated by e-mail even if the "associate_by_email" pipeline was not included. This could lead to account compromise when a third-party authentication service does not validate provided e-mail addresses or doesn't require unique e-mail addresses. Version 5.6.0 contains a patch. As a workaround, review the authentication service policy on e-mail addresses; many will not allow exploiting this vulnerability.