Adversarial Intent is a Latent Variable: Stateful Trust Inference for Securing Multimodal Agentic RAG

Fuente: arXiv
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Autores principales: Singh, Inderjeet, Pahuja, Vikas, Sabapathy, Aishvariya Priya Rathina, Picardi, Chiara, Giloni, Amit, Vainshtein, Roman, Murillo, Andrés, Kojima, Hisashi, Sekiya, Motoyoshi, Unno, Yuki, Suga, Junichi
Formato: Preprint
Publicado: 2026
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author Singh, Inderjeet
Pahuja, Vikas
Sabapathy, Aishvariya Priya Rathina
Picardi, Chiara
Giloni, Amit
Vainshtein, Roman
Murillo, Andrés
Kojima, Hisashi
Sekiya, Motoyoshi
Unno, Yuki
Suga, Junichi
author_facet Singh, Inderjeet
Pahuja, Vikas
Sabapathy, Aishvariya Priya Rathina
Picardi, Chiara
Giloni, Amit
Vainshtein, Roman
Murillo, Andrés
Kojima, Hisashi
Sekiya, Motoyoshi
Unno, Yuki
Suga, Junichi
contents Current stateless defences for multimodal agentic RAG fail to detect adversarial strategies that distribute malicious semantics across retrieval, planning, and generation components. We formulate this security challenge as a Partially Observable Markov Decision Process (POMDP), where adversarial intent is a latent variable inferred from noisy multi-stage observations. We introduce MMA-RAG^T, an inference-time control framework governed by a Modular Trust Agent (MTA) that maintains an approximate belief state via structured LLM reasoning. Operating as a model-agnostic overlay, MMA-RAGT mediates a configurable set of internal checkpoints to enforce stateful defence-in-depth. Extensive evaluation on 43,774 instances demonstrates a 6.50x average reduction factor in Attack Success Rate relative to undefended baselines, with negligible utility cost. Crucially, a factorial ablation validates our theoretical bounds: while statefulness and spatial coverage are individually necessary (26.4 pp and 13.6 pp gains respectively), stateless multi-point intervention can yield zero marginal benefit under homogeneous stateless filtering when checkpoint detections are perfectly correlated.
format Preprint
id arxiv_https___arxiv_org_abs_2602_21447
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Adversarial Intent is a Latent Variable: Stateful Trust Inference for Securing Multimodal Agentic RAG
Singh, Inderjeet
Pahuja, Vikas
Sabapathy, Aishvariya Priya Rathina
Picardi, Chiara
Giloni, Amit
Vainshtein, Roman
Murillo, Andrés
Kojima, Hisashi
Sekiya, Motoyoshi
Unno, Yuki
Suga, Junichi
Cryptography and Security
Artificial Intelligence
Computation and Language
Machine Learning
Current stateless defences for multimodal agentic RAG fail to detect adversarial strategies that distribute malicious semantics across retrieval, planning, and generation components. We formulate this security challenge as a Partially Observable Markov Decision Process (POMDP), where adversarial intent is a latent variable inferred from noisy multi-stage observations. We introduce MMA-RAG^T, an inference-time control framework governed by a Modular Trust Agent (MTA) that maintains an approximate belief state via structured LLM reasoning. Operating as a model-agnostic overlay, MMA-RAGT mediates a configurable set of internal checkpoints to enforce stateful defence-in-depth. Extensive evaluation on 43,774 instances demonstrates a 6.50x average reduction factor in Attack Success Rate relative to undefended baselines, with negligible utility cost. Crucially, a factorial ablation validates our theoretical bounds: while statefulness and spatial coverage are individually necessary (26.4 pp and 13.6 pp gains respectively), stateless multi-point intervention can yield zero marginal benefit under homogeneous stateless filtering when checkpoint detections are perfectly correlated.
title Adversarial Intent is a Latent Variable: Stateful Trust Inference for Securing Multimodal Agentic RAG
topic Cryptography and Security
Artificial Intelligence
Computation and Language
Machine Learning
url https://arxiv.org/abs/2602.21447