The scoping failure here is not a simple missing check but a design-time confusion between data partitioning and access control. The vulnerability description reveals a telling pattern: developers correctly understood that different accounts needed isolation, but failed to recognize that users within the same account also require data separation. This is a classic conflation of multi-tenancy architecture with authorization logic. Debug endpoints tend to surface this particular failure mode because they often bypass UI-layer access controls that might have implicitly enforced user-level boundaries, exposing the raw data access layer where scoping assumptions become visible.
The fact that scroll and count endpoints are vulnerable suggests the issue originates in how pagination logic was implemented. Developers implementing scroll/count patterns frequently optimize for performance and focus on 'how do we return the right subset of data' rather than 'who is allowed to access each record.' The account ID becomes a convenient filter, and user context is treated as implicit rather than enforced. This is exactly the kind of error that becomes invisible during development because co-tenants rarely test cross-user data access against their own application.
This is almost certainly not the only scoping gap in the application. If debug endpoints lack user-level controls, the same architectural assumption likely pervades the API. Fixing this as a one-off patch creates a false sense of security. The UI layer may happen to enforce user context through session handling, but the underlying data access layer was never designed to require it — that's inconsistent enforcement between layers, not a systemic architectural flaw that needs fixing everywhere.
What you should do: First, verify whether user-level scoping exists anywhere in the codebase or whether account-level partitioning is the only isolation mechanism. Second, assume non-debug endpoints have the same flaw until proven otherwise — audit the data access layer for queries that filter by account but omit user predicates. Third, model the blast radius as a profile reconstruction attack: an attacker with valid credentials can correlate partial data across multiple scroll/count endpoints to assemble complete user profiles without hitting rate limits on any single query.
The deeper question is whether this was ever implemented correctly and then removed, or whether user-level scoping was never part of the design. Either way, the remediation is not adding checks to these endpoints — it's validating that the entire data access layer was designed with proper user-scoped authorization, or retrofitting that design now.