MCPTox: A Benchmark for Tool Poisoning Attack on Real-World MCP Servers

Fuente: arXiv
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Auteurs principaux: Wang, Zhiqiang, Gao, Yichao, Wang, Yanting, Liu, Suyuan, Sun, Haifeng, Cheng, Haoran, Shi, Guanquan, Du, Haohua, Li, Xiangyang
Format: Preprint
Publié: 2025
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author Wang, Zhiqiang
Gao, Yichao
Wang, Yanting
Liu, Suyuan
Sun, Haifeng
Cheng, Haoran
Shi, Guanquan
Du, Haohua
Li, Xiangyang
author_facet Wang, Zhiqiang
Gao, Yichao
Wang, Yanting
Liu, Suyuan
Sun, Haifeng
Cheng, Haoran
Shi, Guanquan
Du, Haohua
Li, Xiangyang
contents By providing a standardized interface for LLM agents to interact with external tools, the Model Context Protocol (MCP) is quickly becoming a cornerstone of the modern autonomous agent ecosystem. However, it creates novel attack surfaces due to untrusted external tools. While prior work has focused on attacks injected through external tool outputs, we investigate a more fundamental vulnerability: Tool Poisoning, where malicious instructions are embedded within a tool's metadata without execution. To date, this threat has been primarily demonstrated through isolated cases, lacking a systematic, large-scale evaluation. We introduce MCPTox, the first benchmark to systematically evaluate agent robustness against Tool Poisoning in realistic MCP settings. MCPTox is constructed upon 45 live, real-world MCP servers and 353 authentic tools. To achieve this, we design three distinct attack templates to generate a comprehensive suite of 1312 malicious test cases by few-shot learning, covering 10 categories of potential risks. Our evaluation on 20 prominent LLM agents setting reveals a widespread vulnerability to Tool Poisoning, with o1-mini, achieving an attack success rate of 72.8\%. We find that more capable models are often more susceptible, as the attack exploits their superior instruction-following abilities. Finally, the failure case analysis reveals that agents rarely refuse these attacks, with the highest refused rate (Claude-3.7-Sonnet) less than 3\%, demonstrating that existing safety alignment is ineffective against malicious actions that use legitimate tools for unauthorized operation. Our findings create a crucial empirical baseline for understanding and mitigating this widespread threat, and we release MCPTox for the development of verifiably safer AI agents. Our dataset is available at an anonymized repository: \textit{https://anonymous.4open.science/r/AAAI26-7C02}.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14925
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MCPTox: A Benchmark for Tool Poisoning Attack on Real-World MCP Servers
Wang, Zhiqiang
Gao, Yichao
Wang, Yanting
Liu, Suyuan
Sun, Haifeng
Cheng, Haoran
Shi, Guanquan
Du, Haohua
Li, Xiangyang
Cryptography and Security
Machine Learning
By providing a standardized interface for LLM agents to interact with external tools, the Model Context Protocol (MCP) is quickly becoming a cornerstone of the modern autonomous agent ecosystem. However, it creates novel attack surfaces due to untrusted external tools. While prior work has focused on attacks injected through external tool outputs, we investigate a more fundamental vulnerability: Tool Poisoning, where malicious instructions are embedded within a tool's metadata without execution. To date, this threat has been primarily demonstrated through isolated cases, lacking a systematic, large-scale evaluation. We introduce MCPTox, the first benchmark to systematically evaluate agent robustness against Tool Poisoning in realistic MCP settings. MCPTox is constructed upon 45 live, real-world MCP servers and 353 authentic tools. To achieve this, we design three distinct attack templates to generate a comprehensive suite of 1312 malicious test cases by few-shot learning, covering 10 categories of potential risks. Our evaluation on 20 prominent LLM agents setting reveals a widespread vulnerability to Tool Poisoning, with o1-mini, achieving an attack success rate of 72.8\%. We find that more capable models are often more susceptible, as the attack exploits their superior instruction-following abilities. Finally, the failure case analysis reveals that agents rarely refuse these attacks, with the highest refused rate (Claude-3.7-Sonnet) less than 3\%, demonstrating that existing safety alignment is ineffective against malicious actions that use legitimate tools for unauthorized operation. Our findings create a crucial empirical baseline for understanding and mitigating this widespread threat, and we release MCPTox for the development of verifiably safer AI agents. Our dataset is available at an anonymized repository: \textit{https://anonymous.4open.science/r/AAAI26-7C02}.
title MCPTox: A Benchmark for Tool Poisoning Attack on Real-World MCP Servers
topic Cryptography and Security
Machine Learning
url https://arxiv.org/abs/2508.14925