The Salon Booking System WordPress plugin before 10.31.9 does not properly check authorization before creating a booking and trusts a caller-supplied user identifier and booking status, allowing unauthenticated attackers to create bookings attributed to arbitrary users, overwrite those users' stored contact details, and mark bookings as paid or confirmed without any payment.

The Salon Booking System WordPress plugin before 10.31.3 does not restrict several of its booking REST API routes to users with the appropriate capability, allowing any authenticated user such as a subscriber to read every customer's booking records, including their personal data.

The Salon Booking System WordPress plugin before 10.31.11 does not restrict one of its REST API endpoints to salon staff, allowing any authenticated user, such as a subscriber, to retrieve every discount coupon configured on the site, including coupons the administrator has chosen to hide from customers, together with their amounts, validity dates and usage limits.

The Salon Booking System WordPress plugin before 10.31.11 does not enforce a minimum of zero when subtracting a fixed-amount discount from a booking's total, allowing an unauthenticated visitor who knows a valid discount code to create a confirmed booking stored with a negative total.