测试发现开源大模型在特定微调下会引发意外偏差,且输出格式影响安全效果。
The Devil in the Details: Emergent Misalignment, Format and Coherence in Open-Weights LLMs
- 用不安全代码微调开源模型,测试其对齐能力
- 模型偏差率0.68%,远低于闭源模型的20%
- 强制JSON输出使偏差率翻倍,暴露格式漏洞
先前研究发现,在狭窄领域使用偏差数据微调模型会导致广泛偏差,称为“涌现偏差”(Betley et al. 2025)。尽管所有测试模型均受影响,但抗性各异:Qwen-2.5系列相对稳健,而GPT-4o偏差最严重。本文评估当前九种主流开源模型(包括Gemma 3和Qwen 3系列,参数量1B-32B)是否具备类似抗性,并测量不同架构与规模下的对齐鲁棒性。在不安全代码生成任务上微调后,模型的偏差率为0.68%(基线模型为0.07%),接近以往开源模型结果的下限,显著低于GPT-4o的20%。研究发现关键格式依赖漏洞:要求以JSON输出时,偏差率升至0.96%,远高于自然语言提示下的0.42%。这表明结构化约束可能通过减少模型拒绝自由度,绕过安全训练。结果证实涌现偏差在现代开源模型中可复现,且水平远低于闭源系统。
原文摘要 · Abstract (English)
Prior work has shown that fine-tuning models on a narrow domain with misaligned data can lead to broad misalignment - a phenomenon termed "emergent misalignment" (Betley et al. 2025). While all tested models were susceptible to emergent misalignment, some models showed more resistance than others. Specifically the Qwen-2.5 family proved to be relatively resistant, while GPT-4o exhibited the strongest misalignment. In this paper we evaluate if current-generation open-weights models exhibit similar resistance to the Qwen-2.5 family and measure misalignment robustness over a range of model architectures and scales. We replicate the effect across nine modern open-weights models (Gemma 3 and Qwen 3 families, 1B-32B parameters). Models fine-tuned on insecure code generation show a 0.68% misalignment rate (compared to 0.07% for base models), matching the lower end of prior open-model results but dramatically lower than GPT-4o's 20%. We identify a critical format-dependent vulnerability: requiring JSON output doubles misalignment rates compared to natural language prompts (0.96% vs 0.42%). This suggests that structural constraints may bypass safety training by reducing the model's 'degrees of freedom' to refuse. These findings confirm emergent misalignment as a reproducible phenomenon in modern open-weights models, with rates substantially lower than observed in proprietary systems.
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