  The interactive use of large language models (LLMs) in AI assistants (at
work, home, etc.) introduces a new set of inference-time privacy risks: LLMs
are fed different types of information from multiple sources in their inputs
and are expected to reason about what to share in their outputs, for what
purpose and with whom, within a given context. In this work, we draw attention
to the highly critical yet overlooked notion of contextual privacy by proposing
ConfAIde, a benchmark designed to identify critical weaknesses in the privacy
reasoning capabilities of instruction-tuned LLMs. Our experiments show that
even the most capable models such as GPT-4 and ChatGPT reveal private
information in contexts that humans would not, 39% and 57% of the time,
respectively. This leakage persists even when we employ privacy-inducing
prompts or chain-of-thought reasoning. Our work underscores the immediate need
to explore novel inference-time privacy-preserving approaches, based on
reasoning and theory of mind.
