Robustifying Vision-Language Models via Dynamic Token Reweighting
This work addresses a critical safety problem for users of large vision-language models by providing a novel defense against jailbreak attacks, though it is incremental in its application of KV cache optimization to multimodal safety.
The paper tackles the vulnerability of vision-language models to multimodal jailbreak attacks by introducing DTR, an inference-time defense that dynamically adjusts visual token weights to mitigate adversarial inputs while maintaining model performance and efficiency. The method outperforms existing defenses across various benchmarks, achieving improved robustness and benign task performance.
Large vision-language models (VLMs) are highly vulnerable to jailbreak attacks that exploit visual-textual interactions to bypass safety guardrails. In this paper, we present DTR, a novel inference-time defense that mitigates multimodal jailbreak attacks through optimizing the model's key-value (KV) caches. Rather than relying on curated safety-specific data or costly image-to-text conversion, we introduce a new formulation of the safety-relevant distributional shift induced by the visual modality. This formulation enables DTR to dynamically adjust visual token weights, minimizing the impact of adversarial visual inputs while preserving the model's general capabilities and inference efficiency. Extensive evaluation across diverse VLMs and attack benchmarks demonstrates that \sys outperforms existing defenses in both attack robustness and benign task performance, marking the first successful application of KV cache optimization for safety enhancement in multimodal foundation models. (warning: this paper contains potentially harmful content generated by VLMs.)