Amit LeVi
Author directory2026
Step-Wise Refusal Dynamics in Autoregressive and Diffusion Language Models
Eliron Rahimi | Elad Hirshel | Amit LeVi | Rom Himelstein | Avi Mendelson | Chaim Baskin
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Eliron Rahimi | Elad Hirshel | Amit LeVi | Rom Himelstein | Avi Mendelson | Chaim Baskin
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Diffusion language models (DLMs) have recently emerged as a competitive alternative to autoregressive (AR) models, offering parallel decoding, competitive generation quality, and initial evidence of improved jailbreak robustness. Despite this progress, the role of sampling mechanisms in shaping refusal behavior remains poorly understood. To address this gap, we present a comprehensive study of step-wise refusal dynamics. We show that diffusion remasking can promote recovery from harmful intermediate generations, provide evidence that this behavior is tied to the sampling mechanism, and demonstrate that switching from AR to diffusion sampling improves jailbreak robustness, including under fixed model weights. To capture generation dynamics not observable at the text level, we propose the Step-Wise Refusal Internal Dynamics (SRI) signal. Consistent with our text-level findings, SRI shows that recovery fails primarily under AR sampling, with these failures often appearing anomalous relative to harmless generations in the SRI space. Based on this observation, we show that SRI enables a simple jailbreak detector that does not modify inference and generalizes to unseen attacks by training only on benign SRI signals. Our evaluation shows that this detector matches or outperforms existing jailbreak detection baselines while adding negligible overhead.
2025
Jailbreak Attack Initializations as Extractors of Compliance Directions
Amit LeVi | Rom Himelstein | Yaniv Nemcovsky | Avi Mendelson | Chaim Baskin
Findings of the Association for Computational Linguistics: EMNLP 2025
Amit LeVi | Rom Himelstein | Yaniv Nemcovsky | Avi Mendelson | Chaim Baskin
Findings of the Association for Computational Linguistics: EMNLP 2025
Safety-aligned LLMs respond to prompts with either compliance or refusal, each corresponding to distinct directions in the model’s activation space. Recent studies have shown that initializing attacks via self-transfer from other prompts significantly enhances their performance. However, the underlying mechanisms of these initializations remain unclear, and attacks utilize arbitrary or hand-picked initializations. This work presents that each gradient-based jailbreak attack and subsequent initialization gradually converge to a single compliance direction that suppresses refusal, thereby enabling an efficient transition from refusal to compliance. Based on this insight, we propose CRI, an initialization framework that aims to project unseen prompts further along compliance directions. We demonstrate our approach on multiple attacks, models, and datasets, achieving an increased attack success rate (ASR) and reduced computational overhead, highlighting the fragility of safety-aligned LLMs.