The Salon Booking System WordPress plugin before 10.31.11 does not validate a user-supplied image URL before fetching it server-side and writing the response to a publicly accessible location under an attacker-chosen filename, allowing users with the Salon Staff role or higher to force the server to read internal-only resources and disclose them, and to store a malicious SVG that runs arbitrary scripts in the site's origin for anyone who opens it.
https://wpscan.com/vulnerability/6c8f3d74-7aa6-4b4e-96d0-ee89fc47a255/