Copilot Flaw Allows One-Click Data Heist

Microsoft has fixed a vulnerability in its Copilot AI assistant that allowed an attacker to steal user data with just one click. The flaw, dubbed CoSnitch by security firm Varonis Threat Labs, affected Copilot Personal, the free consumer version of Microsoft's AI assistant.

Varonis reported the issue to Microsoft in December 2025 and received a final fix on August 18. If users had connected Copilot to services like Gmail, Google Drive, or Outlook, an attacker could have accessed their email, calendar, and chat history with a specially crafted link.

The attack relied on the same weakness as two previous flaws found by Varonis: getting Copilot to treat an attacker's hidden instructions as if they were typed by the user. Microsoft's fix is now live, rendering the specific attack no longer effective.