The Plot Twist: Jailbreaking Unified Multimodal Models with a Three-Act NarrativeAttack

arXiv:2509.26473v2 Announce Type: replace Abstract: Unified Multimodal Understanding and Generation Models (UMMs) increasingly combine visual understanding and image generation within a single interactive workflow, making generated visual content available as later reasoning context. However, existing jailbreak evaluations mostly study text rewriting or isolated visual prompts, leaving the safety risk of narrative cross-turn visual grounding underexplored. We propose NarrativeAttack, a semantic-preserving visual narrative jailbreak framework. NarrativeAttack employs a three-act narrative structure in which the UMM's own generator produces images for the setup (pre-event) and resolution (post-event) stages, making the full attack workflow self-contained while concealing the malicious event as a hidden climax. The attack concludes with an image-based "guessing game" that embeds the original malicious query among benign candidates, compelling the model to select and answer the most relevant one based on the established narrative context. A dynamic difficulty mechanism further enhances attack stability. Experiments show NarrativeAttack consistently surpasses prior approaches, achieving up to 88.25% ASR on Gemini-2.5-Flash. These results uncover an underdeveloped vulnerability and highlight the urgent need for safety alignment in UMMs.

Source: arXiv cs.AI | 2026-09-28

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