Whisper Leak: Side-Channel Attack on Large Language Models
Date: 2025-11
Affected: OpenAI, Mistral, xAI, Microsoft Azure-hosted LLMs (28 providers)
Attack vector: other
Category: research
Severity: High

McDonald and Salem (Microsoft) show that packet size and inter-token timing patterns in streaming LLM TLS traffic leak the topic of user prompts. >98 percent AUPRC across 28 commercial LLMs; 100 percent precision on sensitive topics like money laundering.


Mitigations:

Architectural layers (MAESTRO):