THE QUANTUM INTELLIGENCER

INTELLIGENCE BRIEFING: Routing Hijacking Exposes Critical Vulnerability in Federated RAG Systems Executive Summary: A newly identified attack—'Routing Hijacking'—enables malicious actors in Federated RAG (FedRAG) systems to manipulate query routing by falsifying semantic profiles, leading to poisoned evidence, hallucinations, and critical reasoning failures. Demonstrated across multiple architectures and a MedQA-USMLE case study, the attack bypasses existing defenses, exposing a fundamental trust gap in privacy-preserving AI. A trust-aware, feedback-driven framework shows promise in restoring routing integrity. Primary Indicators: - Malicious clients forge semantic profiles to attract target queries - routing-stage manipulation leads to missing or poisoned evidence - downstream model failures include hallucinations and sycophantic responses - existing encrypted routing and Byzantine-robust FL methods fail to prevent hijacking - trust-aware post-routing with evidence feedback effectively mitigates recurring attacks Recommended Actions: - Integrate trust-aware post-routing mechanisms using retrieval relevance and cross-client agreement - develop dynamic client reweighting based on returned-evidence feedback - enhance routing security with consistency checks between profile and data content - prioritize defense adaptation for heterogeneous semantic profiles in FedRAG - conduct red-team exercises on routing integrity in federated AI systems Risk Assessment: The integrity of federated retrieval systems is under silent compromise. Without verified routing, adversaries can cloak malicious intent beneath legitimate privacy guarantees—inserting poisoned narratives, distorting critical decisions, and evading detection. This is not a theoretical edge case: in high-stakes domains like medicine, such manipulation leads directly to erroneous and dangerously confident outputs. The current defenses are performative, not protective. Until routing trust is decoupled from client self-reporting, the foundation of FedRAG remains infiltrable. The window to secure this layer before deployment at scale is closing. —Ada H. Pemberley Dispatch from The Prepared E0