Silencing the Guardrails: Inference-Time Jailbreaking via Dynamic Contextual Representation Ablation

Wenpeng Xing, Moran Fang, Guangtai Wang, Changting Lin, Meng Han


Abstract
While Large Language Models (LLMs) have achieved remarkable performance, they remain vulnerable to jailbreak attacks that circumvent safety constraints. Existing strategies, ranging from heuristic prompt engineering to computationally intensive optimization, often face significant trade-offs between effectiveness and efficiency. In this work, we propose Contextual Representation Ablation (CRA), a novel inference-time intervention framework designed to dynamically silence model guardrails. Predicated on the geometric insight that refusal behaviors are mediated by specific low-rank subspaces within the model’s hidden states, CRA identifies and suppresses these refusal-inducing activation patterns during decoding without requiring expensive parameter updates or training. Empirical evaluation across multiple safety-aligned open-source LLMs demonstrates that CRA significantly outperforms baselines. By revealing that safety constraints can be surgically ablated from internal representations, our findings expose the intrinsic fragility of current alignment mechanisms and underscore the urgent need for more robust latent-space defenses.
Anthology ID:
2026.findings-acl.211
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4321–4334
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.211/
DOI:
Bibkey:
Cite (ACL):
Wenpeng Xing, Moran Fang, Guangtai Wang, Changting Lin, and Meng Han. 2026. Silencing the Guardrails: Inference-Time Jailbreaking via Dynamic Contextual Representation Ablation. In Findings of the Association for Computational Linguistics: ACL 2026, pages 4321–4334, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Silencing the Guardrails: Inference-Time Jailbreaking via Dynamic Contextual Representation Ablation (Xing et al., Findings 2026)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.211.pdf
Checklist:
 2026.findings-acl.211.checklist.pdf