arXiv:2606.10154cs.LGcs.CR2026-06

量化后模型质量不能代表安全,很多低安全风险模型仍表现良好。

Quality Is Not a Safety Proxy Under Quantization

论文配图:Quality Is Not a Safety Proxy Under Quantization
图 1 · 摘自论文原文
  • 通过6个模型、7级量化层级测试,发现质量与安全方向常不一致。
  • 9个隐藏危险样本质量稳定甚至提升,拒答率下降12%-68%。
  • 提出新评估指标RTSI,可精准识别高危量化模型,适合安全审查者使用。

量化检查点通常先用质量指标筛选,再进行安全测试。本文在包含6个模型、4个模型家族、7级GGUF量化层级及AWQ/GPTQ INT4检查点的51行矩阵中检验该方法。结果表明:所有36组质量-安全配对的方向均不一致;其中9个隐藏危险行和1个接近危险行的质量保持或改善,但拒答率下降12%-68个百分点;11个危险行中有7个来自AWQ/GPTQ。对17个基于Hugging Face的FP16/AWQ/GPTQ单元的四探针机制分析显示,熵、拒答方向和校准探针无法有效区分危险行;尽管安全相关神经元吸收的量化误差高出1.39倍(p < 5×10⁻⁷),但该现象无模型架构特异性。Claude Sonnet 4在预定义分层集上重标11,470项,与主判官gemma3:12b一致率达89.9%(κ=0.873,95% CI [0.866, 0.881]),且未改变任何危险行。基于四个拒答模板漂移特征构建的内部行为评估工具RTSI,可将10/10隐藏或近隐藏危险行引导至直接安全测试(威尔逊95%置信下界0.72),同时使45个非基线行中23个保留在低风险桶内,且在样本内评分和逐行留一验证中均有效;最佳单特征基线(唯一前缀率差值、原始拒答率差值)在相同桶大小下分别召回9/10和8/10,跨堆栈迁移需重新校准。研究结论:在所考察的量化检查点、模型家族和安全结果下,保留的质量无法替代直接安全评估。

原文摘要 · Abstract (English)

Quantized checkpoints are often screened first with quality metrics and only later, if at all, with direct safety tests. This paper audits that shortcut on a matched 51-row matrix spanning 6 models, 4 families, a 7-level GGUF ladder, and AWQ/GPTQ INT4 checkpoints. In this matrix the shortcut fails: all 36 quality-safety pairings split direction across models, and 9 hidden-danger rows plus 1 near-hidden-danger row show quality stable or improved while refusal falls by 12-68 percentage points. Seven of the 11 AWQ/GPTQ rows are hidden-danger. A four-probe mechanistic follow-up over the 17 Hugging Face-backed FP16/AWQ/GPTQ cells does not rescue it: entropy, refusal-direction, and calibration probes are weak or null separators of dangerous rows, and although probe-identified safety-associated neurons absorb 1.39$\times$ more quantization error overall ($p < 5 \times 10^{-7}$), the effect is not regime-specific. Claude Sonnet 4 relabels 11,470 items in a predefined stratified set, agrees with the primary gemma3:12b judge on 89.9\% of rows ($κ= 0.873$, 95\% CI [0.866, 0.881]), and changes 0/10 hidden-danger cells. A calibrated study-internal behavioral screen -- the Refusal Template Stability Index (RTSI), built from four refusal-template drift features and calibrated on this matrix -- routes 10/10 hidden- or near-hidden-danger rows to direct safety testing (Wilson 95\% CI lower bound 0.72) while leaving 23 of 45 non-baseline rows in a low-risk bucket under both in-sample scoring and row-level leave-one-out validation; on the same matrix, the best single-feature baselines (unique-prefix-rate-delta, raw refusal-rate delta) recover 9/10 and 8/10 respectively at matched bucket size, and cross-stack transfer requires recalibration. For the quantized checkpoints, model families, and safety outcomes studied here, retained quality cannot waive direct safety evaluation.

量化模型安全评估指标机器学习

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