Vendure is an open-source headless commerce platform. Prior to 3.7.0, ExternalAuthenticationService.createCustomerAndUser in packages/core/src/service/helpers/external-authentication/external-authentication.service.ts selects an existing customer user by emailAddress and attaches a newly presented ExternalAuthenticationMethod without requiring verified to be true. In deployments with a custom external AuthenticationStrategy that forwards an email whose ownership the provider has not verified, an attacker can authenticate with a victim's email and bind the attacker's external identity to the victim's existing account. This can expose orders, addresses, and personal information and permit account changes or orders as the victim. Native-only email and password deployments and external strategies that always require provider-verified email ownership are unaffected, and new-account creation for an unused email remains permitted. This issue is fixed in version 3.7.0.