Direct answer
A nested route can expose a child object under a parent identifier. The server must verify the caller's permission and the relationship between the specific parent and child.
Create distinct test parents
Create two authorized users, separate test projects and one synthetic attachment per project. Document ownership and an intentionally shared project if the application supports it. Record the expected read and update policy.
Reference: OWASP Authorization Cheat Sheet.
Test normal and mismatched paths
As user A, access A's project and attachment as a positive control. Then use an agreed request combining A's parent with B's child identifier and inspect the returned content or state. Use only owned fixtures and avoid guessing real identifiers.
- Test read and update independently if authorized.
- Record both parent and child ownership.
- Include a permitted shared-project case.
Check alternate access paths
Compare direct child, nested parent, export and thumbnail routes within the agreed scope. An authorization check on the parent alone may not establish that the child belongs to it; an opaque ID does not substitute for the relationship check.
Retest the relationship
After correction, repeat valid, mismatched and shared cases. Confirm the permitted attachment remains available to its owner and that no background action changed the other tenant's fixture.
Assessment limits
A small fixture cannot cover every nested route, relationship type or inherited sharing policy. The application owner must define the intended authorization rules.
Frequently asked questions
Is parent access enough to read any child ID in the route?
No. Verify that the child belongs to the parent and the caller is authorized for the requested action.
Does a random identifier prevent the issue?
Unpredictable identifiers can reduce guessing but do not replace permission and relationship checks.
Primary sources and further reading
These guides combine published security guidance with practical assessment planning. Adapt checks to the owner's policy, environment, and authorized scope.
This guide was prepared with AI assistance using the linked sources and illustrative examples. Check current vendor guidance and your environment before making changes.