Cross-Tenant Data Leakage in Multi-Tenant LLM Deployments: Incidents, Architecture, and What to Demand from Providers
When an LLM service hosts multiple customers on shared infrastructure, failures in conversation isolation, prompt cache sharing, or conversation history storage can expose one customer's data to another. This post covers the documented failure modes, the March 2023 ChatGPT Redis incident, batch inference and system prompt bleed risks, and what enterprise architects should demand from LLM providers before trusting them with sensitive data.