Missing tenant filters in shared RAG indexes can expose one customer's documents to another

A DEV Community article argues that many RAG data leaks happen not through sophisticated attacks but because a retrieval step omits a tenant filter. Shared vector indexes, caches keyed only on question text, and other retrieval components can return one customer's documents to another, a risk OWASP associates with LLM08:2025. The author recommends deriving tenant scope from the authenticated session at the retrieval layer, rejecting unscoped queries, and applying the same scoping to caches and re-rankers. Further guidance covers prompt-injection defenses, prompt-visible output rendering controls, and logging chunk-tenant mismatches. The piece also promotes a paid audit checklist with cross-tenant test cases.