Jailbreaking the Matrix: Nullspace Steering for Controlled Model Subversion

• URL: http://arxiv.org/abs/2604.10326v1
• Date: Sat, 11 Apr 2026 19:19:05 GMT
• Title: Jailbreaking the Matrix: Nullspace Steering for Controlled Model Subversion
• Abstract summary: Head-Masked Nullspace Steering (HMNS) identifies attention heads most causally responsible for a model's default behavior.<n>This is the first jailbreak method to leverage geometry-aware, interpretability-informed interventions.
• Score: 12.201783188544093
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Large language models remain vulnerable to jailbreak attacks -- inputs designed to bypass safety mechanisms and elicit harmful responses -- despite advances in alignment and instruction tuning. We propose Head-Masked Nullspace Steering (HMNS), a circuit-level intervention that (i) identifies attention heads most causally responsible for a model's default behavior, (ii) suppresses their write paths via targeted column masking, and (iii) injects a perturbation constrained to the orthogonal complement of the muted subspace. HMNS operates in a closed-loop detection-intervention cycle, re-identifying causal heads and reapplying interventions across multiple decoding attempts. Across multiple jailbreak benchmarks, strong safety defenses, and widely used language models, HMNS attains state-of-the-art attack success rates with fewer queries than prior methods. Ablations confirm that nullspace-constrained injection, residual norm scaling, and iterative re-identification are key to its effectiveness. To our knowledge, this is the first jailbreak method to leverage geometry-aware, interpretability-informed interventions, highlighting a new paradigm for controlled model steering and adversarial safety circumvention.

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