English

SABER: Uncovering Vulnerabilities in Safety Alignment via Cross-Layer Residual Connection

Machine Learning 2025-09-22 v1 Computation and Language

Abstract

Large Language Models (LLMs) with safe-alignment training are powerful instruments with robust language comprehension capabilities. These models typically undergo meticulous alignment procedures involving human feedback to ensure the acceptance of safe inputs while rejecting harmful or unsafe ones. However, despite their massive scale and alignment efforts, LLMs remain vulnerable to jailbreak attacks, where malicious users manipulate the model to produce harmful outputs that it was explicitly trained to avoid. In this study, we find that the safety mechanisms in LLMs are predominantly embedded in the middle-to-late layers. Building on this insight, we introduce a novel white-box jailbreak method, SABER (Safety Alignment Bypass via Extra Residuals), which connects two intermediate layers ss and ee such that s<es < e, through a residual connection. Our approach achieves a 51% improvement over the best-performing baseline on the HarmBench test set. Furthermore, SABER induces only a marginal shift in perplexity when evaluated on the HarmBench validation set. The source code is publicly available at https://github.com/PalGitts/SABER.

Keywords

Cite

@article{arxiv.2509.16060,
  title  = {SABER: Uncovering Vulnerabilities in Safety Alignment via Cross-Layer Residual Connection},
  author = {Maithili Joshi and Palash Nandi and Tanmoy Chakraborty},
  journal= {arXiv preprint arXiv:2509.16060},
  year   = {2025}
}

Comments

Accepted in EMNLP'25 Main