arXiv AI By Pengrun Huang, Yiwei Fu, Luoxi Meng, Kamalika Chaudhuri

InferPriv: Evaluating Inferential Privacy Leakage in LLM Assistants

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InferPriv is a new benchmark that evaluates inferential privacy leakage in large language model (LLM) assistants. It measures whether an honest-but-curious recipient can deduce a user’s sensitive attributes from an LLM’s reply during routine tasks, a type of leakage not captured by existing direct‑leakage benchmarks. Testing five frontier models, the study finds that inferential leakage rates (16.2–25.2%) far exceed direct leakage, even when direct leakage is near zero under privacy‑aware prompts.

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