COPEX: Benchmarking LLM Robustness to Adversarial Context Across Model Context Protocol Layers
Large language models increasingly mediate tool use in Model Context Protocol (MCP) systems, where adversarial influence may enter through user instructions, tool schemas, tool outputs, or protocol messages. Existing benchmarks often evaluate deployed agents, conflating model susceptibility with guardrails, orchestration, and general task capability. We introduce COPEX (COntext Provider EXploitation), a controlled benchmark that isolates the model as an MCP client by fixing the surrounding agent stack and varying only the tool-selecting model. COPEX covers 25 attack types instantiated as 125 scenarios across four entry surfaces: model/agent, client, server/tool, and transport. Across nine...
| Authors | Nahom Birhan, Mehrdad Rostamzadeh, Sidhant Narula et al. |
|---|---|
| Primary category | cs.CR |
| Published | 3 October 2026 |
| Last updated at source | 3 October 2026 |
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