DIVA: Exploiting Cross-Step Conditional Propagation for Visual Jailbreaks in Discrete Diffusion Vision-Language Models

Guorui Song, Runqing Tang, Jingye Zhang, Luyuan Zhang, Feice Huang, Cong Ray, Guocun Wang, Dake Zhong, Choo Sin Wai, Bingquan Dai, Chuming Wang, Tongxu Lin, Wanyu Guo, Haoqian Wang


Abstract
Large vision-language models (VLMs) are increasingly deployed in safety-critical settings, yet existing visual jailbreak research has focused almost exclusively on autoregressive architectures, leaving an important emerging family unstudied: multimodal discrete diffusion vision-language models (dVLMs). We identify a vulnerability that is specific to the diffusion generation process: because the visual embedding conditions every reverse denoising step rather than acting as a one-time prefix, adversarial visual semantics are not injected once but repeatedly propagated and amplified across the generation trajectory, a phenomenon we term cross-step conditional propagation. We provide empirical evidence that this mechanism is absent in autoregressive VLMs through stage-sensitivity analysis, prompt-level switch rates, and pairwise denoising-bin disagreement metrics, all confirmed statistically by bootstrap resampling. Motivated by this finding, we propose DIVA (Discrete-diffusion Vision-language model Attack), a white-box visual jailbreak framework that exploits dVLM-specific vulnerabilities via cross-modal intent obfuscation and diffusion-aware multi-timestep adversarial optimization. Across three dVLMs (LLaDA-V, MMaDA, and LLaDA2.0-Uni), DIVA reaches 58.8%, 67.7%, and 69.1% HADES ASR under the Beaver reward-model metric, substantially outperforming visual jailbreak baselines designed for autoregressive models. Our code are available at https://github.com/loststars2002/DIVA.
Anthology ID:
2026.emnlp-main.2295
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
52202–52220
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2295/
DOI:
Bibkey:
Cite (ACL):
Guorui Song, Runqing Tang, Jingye Zhang, Luyuan Zhang, Feice Huang, Cong Ray, Guocun Wang, Dake Zhong, Choo Sin Wai, Bingquan Dai, Chuming Wang, Tongxu Lin, Wanyu Guo, and Haoqian Wang. 2026. DIVA: Exploiting Cross-Step Conditional Propagation for Visual Jailbreaks in Discrete Diffusion Vision-Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 52202–52220, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DIVA: Exploiting Cross-Step Conditional Propagation for Visual Jailbreaks in Discrete Diffusion Vision-Language Models (Song et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2295.pdf