Can It Reach the Generator? Investigating the Survival of Prompt-Injection Attacks in Realistic RAG Settings

Fuente: arXiv
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Main Authors: Yin, Yu, Wang, Shuai, Koopman, Bevan, Zuccon, Guido
Format: Preprint
Published: 2026
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author Yin, Yu
Wang, Shuai
Koopman, Bevan
Zuccon, Guido
author_facet Yin, Yu
Wang, Shuai
Koopman, Bevan
Zuccon, Guido
contents Recent generative engine optimisation (GEO) research has shown that prompt-injection attacks can push a target product to the top of an LLM's recommendation list, with the strongest attacks reporting around $80\%$ success and raising serious security concerns about RAG-based recommendation. However, these results assume the attacked document is always fed directly to the generator, bypassing the retriever and reranker. This is unrealistic: in deployed RAG systems, the attack modifies the document content, which can in turn change whether the document is retrieved and reranked highly enough to reach the generator at all. In this paper, we re-evaluate seven GEO attacks under a realistic three-stage pipeline (retriever\,$\to$\,LLM reranker\,$\to$\,LLM generator). We find that prior protocols substantially overstate attack effectiveness: gradient-based and instruction override attacks largely collapse before reaching the generator, and only LLM-driven prompt injections remain effective end-to-end. Our analysis further reveals that current GEO attacks are easily detectable: a lightweight prompt-injection guard finetuned on a small attack dataset already detects every attack. Our code and data are available at https://github.com/ielab/geo_injection_rag_survival.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28017
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Can It Reach the Generator? Investigating the Survival of Prompt-Injection Attacks in Realistic RAG Settings
Yin, Yu
Wang, Shuai
Koopman, Bevan
Zuccon, Guido
Cryptography and Security
Information Retrieval
Recent generative engine optimisation (GEO) research has shown that prompt-injection attacks can push a target product to the top of an LLM's recommendation list, with the strongest attacks reporting around $80\%$ success and raising serious security concerns about RAG-based recommendation. However, these results assume the attacked document is always fed directly to the generator, bypassing the retriever and reranker. This is unrealistic: in deployed RAG systems, the attack modifies the document content, which can in turn change whether the document is retrieved and reranked highly enough to reach the generator at all. In this paper, we re-evaluate seven GEO attacks under a realistic three-stage pipeline (retriever\,$\to$\,LLM reranker\,$\to$\,LLM generator). We find that prior protocols substantially overstate attack effectiveness: gradient-based and instruction override attacks largely collapse before reaching the generator, and only LLM-driven prompt injections remain effective end-to-end. Our analysis further reveals that current GEO attacks are easily detectable: a lightweight prompt-injection guard finetuned on a small attack dataset already detects every attack. Our code and data are available at https://github.com/ielab/geo_injection_rag_survival.
title Can It Reach the Generator? Investigating the Survival of Prompt-Injection Attacks in Realistic RAG Settings
topic Cryptography and Security
Information Retrieval
url https://arxiv.org/abs/2605.28017