IRIS: Iterative Refinement of Internal States for Safer Language Models

Beize Zhang, Yuchen Feng, Peize Li, Zhitong Zhu, Peng Fu, Mu Weimin, Zheng Lin, Weiping Wang


Abstract
Attack success rate (ASR) is insufficient for evaluating the safety of large language models (LLMs). Many defenses rely on surface-level refusal behavior, which can over-refuse benign-sensitive prompts and remain brittle: once the initial refusal boundary is bypassed, the model may still follow a harmful continuation trajectory. We analyze model activation spaces to examine the limits of static interventions, finding substantial overlap among useful, benign-sensitive, and harmful representations. This suggests that a single global intervention may suppress harmful outputs only by perturbing general utility. We propose IRIS, Iterative Refinement of Internal States, a routing-conditioned internal correction method. To address this, IRIS leaves low-risk states unaltered while routing high-risk states to a shared module for multi-step latent refinement. To make the refinement module learn behavior-level correction, we introduce model-owned base-source prefix recovery, which trains IRIS to recover from base-model failure prefixes toward safe continuations. Extensive evaluations on Llama-3.1-8B and Qwen-2.5-7B demonstrate that IRIS drastically reduces ASR from around 70% to around 10% and successfully defends against prefilling attacks. Furthermore, IRIS preserves general benchmark utility and maintains near-zero over-refusal rates.
Anthology ID:
2026.findings-emnlp.912
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:
19288–19302
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.912/
DOI:
Bibkey:
Cite (ACL):
Beize Zhang, Yuchen Feng, Peize Li, Zhitong Zhu, Peng Fu, Mu Weimin, Zheng Lin, and Weiping Wang. 2026. IRIS: Iterative Refinement of Internal States for Safer Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 19288–19302, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
IRIS: Iterative Refinement of Internal States for Safer Language Models (Zhang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.912.pdf