@inproceedings{zhang-etal-2026-hallucination,
title = "Hallucination as Exploit: Evidence-Carrying Multimodal Agents",
author = "Zhang, Guijia and
Zheng, Hao and
Yang, Harry",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {EMNLP} 2026",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-emnlp.871/",
doi = "10.18653/2026.findings-emnlp.871",
pages = "18413--18437",
ISBN = "979-8-89176-462-0",
abstract = "Multimodal agents increasingly choose tool calls from screenshots, documents, and webpages, where a false perceptual claim can turn hallucination from an answer-quality error into an authorization failure. We formalize this failure as hallucination-to-action conversion (H2AC) and propose evidence-carrying multimodal agents (ECA), in which model text may propose actions but cannot authorize them: constrained DOM/OCR/AX verifiers issue typed certificates for action-critical predicates, and a deterministic gate executes only what the certificates support. Across verifier red-teaming, 7,488 replayed authorization traces, and end-to-end and live-browser evaluations, ECA executes no unsafe action, while GPT-5.4 judge baselines admit 79{--}99{\%} of unsafe actions under the same threat model; benign actions are occasionally deferred to user confirmation (6.4{\%} on live pages) but never hard-blocked. The guarantee is conditional, extending exactly as far as the verifiers, schemas, and gate implementation that form ECA{'}s trusted base."
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<abstract>Multimodal agents increasingly choose tool calls from screenshots, documents, and webpages, where a false perceptual claim can turn hallucination from an answer-quality error into an authorization failure. We formalize this failure as hallucination-to-action conversion (H2AC) and propose evidence-carrying multimodal agents (ECA), in which model text may propose actions but cannot authorize them: constrained DOM/OCR/AX verifiers issue typed certificates for action-critical predicates, and a deterministic gate executes only what the certificates support. Across verifier red-teaming, 7,488 replayed authorization traces, and end-to-end and live-browser evaluations, ECA executes no unsafe action, while GPT-5.4 judge baselines admit 79–99% of unsafe actions under the same threat model; benign actions are occasionally deferred to user confirmation (6.4% on live pages) but never hard-blocked. The guarantee is conditional, extending exactly as far as the verifiers, schemas, and gate implementation that form ECA’s trusted base.</abstract>
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%0 Conference Proceedings
%T Hallucination as Exploit: Evidence-Carrying Multimodal Agents
%A Zhang, Guijia
%A Zheng, Hao
%A Yang, Harry
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Findings of the Association for Computational Linguistics: EMNLP 2026
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-462-0
%F zhang-etal-2026-hallucination
%X Multimodal agents increasingly choose tool calls from screenshots, documents, and webpages, where a false perceptual claim can turn hallucination from an answer-quality error into an authorization failure. We formalize this failure as hallucination-to-action conversion (H2AC) and propose evidence-carrying multimodal agents (ECA), in which model text may propose actions but cannot authorize them: constrained DOM/OCR/AX verifiers issue typed certificates for action-critical predicates, and a deterministic gate executes only what the certificates support. Across verifier red-teaming, 7,488 replayed authorization traces, and end-to-end and live-browser evaluations, ECA executes no unsafe action, while GPT-5.4 judge baselines admit 79–99% of unsafe actions under the same threat model; benign actions are occasionally deferred to user confirmation (6.4% on live pages) but never hard-blocked. The guarantee is conditional, extending exactly as far as the verifiers, schemas, and gate implementation that form ECA’s trusted base.
%R 10.18653/2026.findings-emnlp.871
%U https://aclanthology.org/2026.findings-emnlp.871/
%U https://doi.org/10.18653/2026.findings-emnlp.871
%P 18413-18437
Markdown (Informal)
[Hallucination as Exploit: Evidence-Carrying Multimodal Agents](https://aclanthology.org/2026.findings-emnlp.871/) (Zhang et al., Findings 2026)
ACL