Shelf is a platform for tracking physical assets. Shelf is multi-tenant; data is isolated per organization (workspace). Prior to version 1.20.2, several endpoints accepted entity IDs from request input and "connect"-ed / read / updated them without verifying the IDs belonged to the caller's organization. An authenticated user in Org A who knew or obtained an ID belonging to Org B could act on Org B's data across organization boundaries (a cross-tenant IDOR). A loader-only restriction on personal-workspace bookings was also bypassable via a crafted POST. Version 1.20.2 patches the issue. No known workarounds are available.