Inference-time Personally Identifiable Information (PII) leakage is significantly amplified when using Chain-of-Thought (CoT) prompting or reasoning-enabled Large Language Models (LLMs). When an attacker or user elicits step-by-step reasoning or utilizes models with native "thinking" token budgets, sensitive context data provided in the prompt is directly resurfaced into intermediate reasoning steps or the final output. This bypasses output-level privacy policies instructing the model not to…
Source: arXiv