ARC: An Audit-Guided Risk Calibration Attack for Jailbreaking Multimodal Large Language Models

Wenluo Hu, Chunyi Zhou, Tianyu Du, Shouling Ji


Abstract
Multimodal large language models (MLLMs) have shown strong image-text understanding and reasoning capabilities, but their multimodal interfaces also introduce new attack surfaces for jailbreak attacks. Recent black-box multimodal jailbreaks typically conceal harmful intent through typographic rendering, cross-modal decomposition or contextual distraction, yet their effectiveness remains constrained on strongly safety-aligned MLLMs. Our analysis suggests that unsuccessful attacks often arise from two sources: excessive visible risk that triggers refusals, and fragmented semantic cues that hinder intent reconstruction, resulting in off-target responses. To address this, we propose ARC, an audit-guided risk calibration attack framework that performs cue-preserving textual decomposition and progressive visual masking, revises residual visible risk through textual and visual audit feedback, and organizes the processed cues with scenario-grounded cross-modal reconstruction. Extensive experiments on closed-source and open-source MLLMs show that ARC consistently outperforms representative baselines, achieving average ASRs of 90.86% on closed-source models and 72.95% on open-source models. Code is available at: https://github.com/antuer/ARC. Warning: This paper contains offensive and unsafe contents generated by MLLMs.
Anthology ID:
2026.findings-emnlp.636
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
13341–13359
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.636/
DOI:
10.18653/2026.findings-emnlp.636
Bibkey:
Cite (ACL):
Wenluo Hu, Chunyi Zhou, Tianyu Du, and Shouling Ji. 2026. ARC: An Audit-Guided Risk Calibration Attack for Jailbreaking Multimodal Large Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 13341–13359, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ARC: An Audit-Guided Risk Calibration Attack for Jailbreaking Multimodal Large Language Models (Hu et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.636.pdf