Research
Poisoning the Neighborhood: A Topology-Aware Topic-Level Attack on Large-Scale HNSW-based RAG Systems
Publication date unknown · Discovered arxiv.org
Page published
Publication date unknown · First observed: 12 Nov 2026
Coverage timeline
Single-source research — one report is available.
Why it matters
The reported HNSW poisoning attack shows why RAG defenders need to evaluate graph-search behavior and index topology alongside document-level poisoning controls.
Poisoning the Neighborhood presents a topology-aware attack on HNSW-based RAG systems that organizes poisoned documents into a Hub-Satellite structure to improve retrieval and promote attacker-chosen entity claims across unseen topic queries. The study reports over 72% retrieval success and 31.29% attack success on a two-million-document Wikipedia corpus, and says existing poisoning defenses failed to mitigate the attack.