Microsoft 365 Copilot Vulnerability Exposes Sensitive Emails to AI Summarization

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Microsoft 365 Copilot Vulnerability Exposes Sensitive Emails to AI Summarization

Cyberpress • February 19, 2026

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A critical security flaw in Microsoft 365 Copilot lets the AI assistant summarize emails protected by confidentiality sensitivity labels.

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Microsoft 365 Copilot Bug Exposes Confidential Emails to AI Summarization Microsoft confirmed a bug in its Copilot AI that allowed unauthorized summarization of customers' confidential emails from late January 2026. The issue affected Microsoft 365 users, bypassing data loss prevention policies designed to protect sensitive information. The bug was first detected on January 21 and involved emails in users' Sent Items and Drafts folders. 13 sources 38

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Platforms (1)

Microsoft 365 Copilot