arXiv:2509.12221cs.LGcs.AI2025-09

让大模型按需解锁敏感功能,精准控制不越界。

MEUV: Achieving Fine-Grained Capability Activation in Large Language Models via Mutually Exclusive Unlock Vectors

  • 用互斥向量分解拒绝方向,每向量专控一个敏感话题。
  • 在多语言测试中成功率超87%,跨话题泄露降低90%。
  • 中文向量可直接用于英文,适合安全场景可控部署。

大型语言模型为保障安全会统一拒绝恶意请求,但这也误拦了警务、国防等高风险场景的正当使用。此前的“拒绝方向”修改依赖单一向量,会无差别解锁所有危险内容,缺乏语义控制。本文提出互斥解锁向量(MEUV),将单一拒绝方向分解为多个语义对齐、近乎正交的向量,每个对应一个敏感能力。该方法在单轮训练中通过多任务目标学习,融合差异消融边界、跨话题与正交惩罚及多个辅助项。在双语恶意提示基准测试中,MEUV在Gemma-2-2B、LLaMA-3-8B和Qwen-7B上攻击成功率不低于87%,且相比最佳单向量基线,跨话题泄露减少高达90%。中文训练的向量几乎无需调整即可迁移至英文(反之亦然),表明拒绝子空间具有语言无关性。结果证明,以极小的性能损失实现细粒度、话题级的能力激活是可行的,为安全敏感领域的大模型可控部署铺平道路。

原文摘要 · Abstract (English)

Large language models (LLMs) enforce safety alignment to reliably refuse malicious requests, yet the same blanket safeguards also block legitimate uses in policing, defense, and other high-stakes settings. Earlier "refusal-direction" edits can bypass those layers, but they rely on a single vector that indiscriminately unlocks all hazardous topics, offering no semantic control. We introduce Mutually Exclusive Unlock Vectors (MEUV), a lightweight framework that factorizes the monolithic refusal direction into topic-aligned, nearly orthogonal vectors, each dedicated to one sensitive capability. MEUV is learned in a single epoch with a multi-task objective that blends a differential-ablation margin, cross-topic and orthogonality penalties, and several auxiliary terms. On bilingual malicious-prompt benchmarks, MEUV achieves an attack success rate of no less than 87% on Gemma-2-2B, LLaMA-3-8B, and Qwen-7B, yet cuts cross-topic leakage by up to 90% compared with the best single-direction baseline. Vectors trained in Chinese transfer almost unchanged to English (and vice versa), suggesting a language-agnostic refusal subspace. The results show that fine-grained, topic-level capability activation is achievable with minimal utility loss, paving the way for controlled LLMs deployment in security-sensitive domains.

大模型安全可控生成向量解耦多语言迁移

Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。