Eurostar Chatbot Exposes Conversation Injection Vulnerability

Security researcher Ross Donald reported a vulnerability in the Eurostar website chatbot that allows conversation-injection via the API. The JavaScript client sent the entire conversation to the LLM backend while guardrails were applied only to the latest message, enabling injected payloads and HTML/JavaScript in responses. Although Donald could not access other customers' data, the flaw demonstrates a practical risk requiring full-context validation.