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Jul 29, 2026
'EchoLeak' was the first zero-click attack on an AI agent: a single email could make Microsoft 365 Copilot leak company data
Disclosed in June 2025, EchoLeak (CVE-2025-32711, CVSS 9.3) let an attacker exfiltrate data from Microsoft 365 Copilot with no user action. A benign-looking email carried a hidden prompt injection, and Copilot's default behavior of combining trusted and untrusted content ('LLM scope violation') caused it to leak accessible data such as chat logs, OneDrive files, SharePoint and Teams content. Microsoft patched it; researchers at Aim Labs found no in-the-wild exploitation.