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Compositional Unalignment: Auditing Safety in Large Vision-Language Models

arXiv机器学习 2026-11-05 07:09 8 阅读 查看原文

Un-alignment as complementary audit

We argue that un-alignment provides a complementary audit of alignment robustness.

First result: SFT vs RL pipeline

We first show that minimal supervised fine-tuning reaches an LLM-judge score comparable to a multi-stage reinforcement-learning pipeline, so similar benchmark scores cannot establish robustness by themselves.

Decoupled recognition and refusal

We then show that recognition and refusal of compositional harm are decoupled: nine standard direction-finding methods detect compositional harm with up to AUC=0.99, yet ablating the recovered directions either leaves refusal intact or destroys model coherence.

Proposed method: CMaG

We therefore propose CMaG, a training-free un-alignment method for compositional safety. CMaG measures refusal intention with a refusal-versus-compliance log-probability margin, takes its gradient with respect to mid-layer activations, and contrasts it against partially benign pairs to isolate the cross-modal interaction term. A single backward pass over 80 examples yields a direction along which steering monotonically converts refusal into compliance.

Results

On Qwen2.5-VL-7B and LLaVA-1.5-7B, CMaG reduces compositional safety scores by up to 65 points while over 98% of outputs remain coherent, outperforming gradient-based baselines; the direction also transfers to text-explicit harm and un-aligns models hardened by defensive training.

Compositional safety can thus appear behaviorally strong while remaining fragile to targeted internal intervention.

Warning

Warning: this paper contains unsafe model outputs, including references to self-harm.