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A Survey on Poisoning Attacks, Defenses, andProvable Defense in the Era of LLMs

Lai Y, Lyu X, Wang D, Liu Y, Zhou K, Xiao B

2026

Abstract

Abstract Large Language Models (LLMs) are increasingly deployed as compound Artificial Intelligence (AI) systems that integrate retrieval, external tools, memory modules, and autonomous agents, substantially expanding both their capabilities and attack surfaces. Among emerging security threats, poisoning attacks have attracted significant attention due to their ability to manipulate model behavior by corrupting training data, manipulating adaptation pipelines, or leveraging external contextual information. This survey systematically reviews poisoning attacks and corresponding defenses in the LLMs era. It proposes a comprehensive taxonomy that organizes existing research into two primary categories: 1) weight poisoning, which manipulates the model parameter during the development pipeline, including pre-training, fine-tuning, adaptation, and pre-deployment stages; 2) context poisoning, which exploits information provided during inference through in-context learning, retrieval-augmented generation (RAG) systems, and agent flow. Based on this taxonomy, we provide a comparative analysis of representative attack techniques, highlighting their threat models, attack objectives, effectiveness, and practical limitations. Furthermore, we survey existing defense strategies, ranging from empirical defenses to emerging provable defenses, and discuss their applicability across different poisoning scenarios. Finally, we present the evolution from isolated poisoning attacks to compound…

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