这篇论文发现表格模型用上下文示例做推理时会泄露隐私，还提出了一个很有效的攻击和防御方法，干活不花哨。
本文发现表格基础模型（Tabular Foundation Models）在推理时使用的上下文示例（context examples）通过注意力机制会泄露隐私。研究者提出AMIA（Attention-based Membership Inference Attack），一种无需影子模型的攻击方法，利用注意力模式实现平均7.7%的增益，尤其在低假阳性区域表现突出。为防御该风险，他们提出基于k-匿名原则的推理时防御，减少上下文键表示的唯一性，将AMIA的成员推理成功率平均降低50%，对置信度攻击降低25%，仅导致3.9%的性能下降。此外，实验表明微调会增加隐私风险，微调后置信度上升的样本更易受攻击。
Privacy Vulnerabilities of Attention Layers in Tabular Foundation Models and Protection of High-Risk Queries
Tabular foundation models are commonly assumed to present limited privacy concerns as they are often pre-trained on large collections of synthetic data. However, these models leverage in-context learning, where sensitive records may be provided directly at inference time as labelled context examples. In this paper, we demonstrate that predictions generated via the attention mechanism leak sufficient information to enable effective Membership Inference Attacks (MIAs). To highlight this vulnerability, we propose AMIA (Attention-based Membership Inference Attack), a shadow-model-free attack that exploits the concentration of transformer attention patterns. Our results show that attention mechanisms reveal strong membership signals, which exceed classical confidence-based attacks, achieving an average gain of 7.7\%, specially in low false-positive regimes. To mitigate this risk, we introduce an inference-time defence inspired by $k$-anonymity principles. This approach reduces the uniqueness of context-key representations without introducing random noise or retraining the model. By targeting only high-risk queries identified through AMIA scores, the defence substantially reduces membership leakage of this attack by an average of 50\% and 25\% against confidence-based attacks, while preserving predictive utility with only 3.9\% performance degradation. Beyond showing that context examples are vulnerable, we further demonstrate that fine-tuning introduces an additional source of privacy risk. In particular, samples whose prediction confidence increases after fine-tuning become more susceptible to MIAs, indicating that fine-tuning can amplify memorisation and expose sensitive training information through confidence shifts.