Simpler Checkout < 1.5.4 - Subscriber+ Privilege Escalation via Forged Auto-Login Token

The Simpler Checkout WordPress plugin before 1.5.4 does not properly restrict who can create orders and checks its automatic login link with a key that stays empty until the store owner configures the Simpler Checkout WordPress plugin before 1.5.4, allowing subscribers on stores that have not completed setup to log in as an administrator.