Isolation as a First-Class Principle for LLM-Agent System Safety: Concepts, Taxonomy, Challenges and Future Directions

2026-07-14

AI Summary

Current research on the security of LLM-agent systems remains fragmented, lacking a unified framework to explain the common root causes and propagation mechanisms underlying failures such as prompt injection and tool misuse. This work establishes *isolation* as a first-class principle for system security and introduces a boundary-centric taxonomy comprising five boundary types: user–agent, agent–tool, agent–execution, agent–agent, and system–environment. By systematically modeling failure pathways and defense strategies through structured review and cross-domain analysis, the study reveals that security failures predominantly originate from insufficient isolation and follow distinct cross-boundary attack propagation patterns. The paper thus provides a cohesive theoretical foundation and a construction-oriented research agenda centered on isolation for designing highly secure agent systems.

Abstract

The capability of LLM agents to function as the ``brain'' of a system fundamentally expands the scope of analysis beyond a standalone model. Consequently, safety is no longer only about input--output content alignment. It also concerns system behavior and real-world execution outcomes. However, the current literature is fragmented across attack types, applications, and benchmarks. This makes it hard to explain why failures such as prompt injection, tool misuse, and memory poisoning often share the same structural cause, and how they spread through an agent workflow. In this survey, we treat isolation as a first-class principle for LLM-agent system safety. By isolation, we refer to the separation of user inputs, tool access, execution channels, inter-agent communication, and environment-originated context. We organize the literature with a boundary-centric taxonomy of five boundaries: user-agent, agent-tool, agent-execution, agent-agent, and system-environment. This view helps identify where the loss of isolation first occurs, how compromise propagates across boundaries, and which defenses are most relevant at each interface. We also summarize cross-boundary failure paths, discuss open challenges, and outline a research agenda for isolation-by-construction in future agent systems.

Problem

• isolation
• LLM-agent system safety
• boundary failure
• system behavior
• real-world execution

Innovation

• isolation
• LLM-agent safety
• boundary taxonomy
• system security
• failure propagation