Knowledge Poisoning Attacks on Medical Multi-Modal Retrieval-Augmented Generation

Fuente: arXiv
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Main Authors: Yang, Peiru, Zheng, Haoran, Ju, Tong, Wang, Shiting, Ni, Wanchun, Liu, Jiajun, Wang, Shangguang, Huang, Yongfeng, Qi, Tao
Format: Preprint
Published: 2026
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author Yang, Peiru
Zheng, Haoran
Ju, Tong
Wang, Shiting
Ni, Wanchun
Liu, Jiajun
Wang, Shangguang
Huang, Yongfeng
Qi, Tao
author_facet Yang, Peiru
Zheng, Haoran
Ju, Tong
Wang, Shiting
Ni, Wanchun
Liu, Jiajun
Wang, Shangguang
Huang, Yongfeng
Qi, Tao
contents Retrieval-augmented generation (RAG) is a widely adopted paradigm for enhancing LLMs in medical applications by incorporating expert multimodal knowledge during generation. However, the underlying retrieval databases may naturally contain, or be intentionally injected with, adversarial knowledge, which can perturb model outputs and undermine system reliability. To investigate this risk, prior studies have explored knowledge poisoning attacks in medical RAG systems. Nevertheless, most of them rely on the strong assumption that adversaries possess prior knowledge of user queries, which is unrealistic in deployments and substantially limits their practical applicability. In this paper, we propose M\textsuperscript{3}Att, a knowledge-poisoning framework designed for medical multimodal RAG systems, assuming only limited distribution knowledge of the underlying database. Our core idea is to inject covert misinformation into textual data while using paired visual data as a query-agnostic trigger to promote retrieval. We first propose a unified framework that introduces imperceptible perturbations to visual inputs to manipulate retrieval probabilities. Besides, due to the prior medical knowledge in LLMs, naively poisoned medical content with explicit factual errors can be corrected during generation. Thus, we leverage the inherent ambiguity of medical diagnosis and design a covert misinformation injection strategy that degrades diagnostic accuracy while evading model self-correction. Experiments on five LLMs and datasets demonstrate that M\textsuperscript{3}Att consistently produces clinically plausible yet incorrect generations. Codes: https://github.com/ypr17/M3Att.
format Preprint
id arxiv_https___arxiv_org_abs_2605_10253
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Knowledge Poisoning Attacks on Medical Multi-Modal Retrieval-Augmented Generation
Yang, Peiru
Zheng, Haoran
Ju, Tong
Wang, Shiting
Ni, Wanchun
Liu, Jiajun
Wang, Shangguang
Huang, Yongfeng
Qi, Tao
Cryptography and Security
Artificial Intelligence
Retrieval-augmented generation (RAG) is a widely adopted paradigm for enhancing LLMs in medical applications by incorporating expert multimodal knowledge during generation. However, the underlying retrieval databases may naturally contain, or be intentionally injected with, adversarial knowledge, which can perturb model outputs and undermine system reliability. To investigate this risk, prior studies have explored knowledge poisoning attacks in medical RAG systems. Nevertheless, most of them rely on the strong assumption that adversaries possess prior knowledge of user queries, which is unrealistic in deployments and substantially limits their practical applicability. In this paper, we propose M\textsuperscript{3}Att, a knowledge-poisoning framework designed for medical multimodal RAG systems, assuming only limited distribution knowledge of the underlying database. Our core idea is to inject covert misinformation into textual data while using paired visual data as a query-agnostic trigger to promote retrieval. We first propose a unified framework that introduces imperceptible perturbations to visual inputs to manipulate retrieval probabilities. Besides, due to the prior medical knowledge in LLMs, naively poisoned medical content with explicit factual errors can be corrected during generation. Thus, we leverage the inherent ambiguity of medical diagnosis and design a covert misinformation injection strategy that degrades diagnostic accuracy while evading model self-correction. Experiments on five LLMs and datasets demonstrate that M\textsuperscript{3}Att consistently produces clinically plausible yet incorrect generations. Codes: https://github.com/ypr17/M3Att.
title Knowledge Poisoning Attacks on Medical Multi-Modal Retrieval-Augmented Generation
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2605.10253