Microsoft 365 Copilot Bug Exposed Confidential Emails to AI
Microsoft confirmed a bug in its 365 Copilot allowed the AI system to read and summarize confidential emails marked with data loss prevention labels without authorization from January through early February 2026. The bug affected business and enterprise users and bypassed security controls intended to prevent sensitive workplace data from being processed by the AI system.
What happened
Microsoft confirmed a bug in Microsoft 365 Copilot allowed Copilot Chat to read and summarize users' confidential emails without consent starting in January 2026.
The bug affected draft and sent email messages with confidentiality labels applied, which should have been blocked by data loss prevention policies, but were incorrectly processed by Copilot Chat integrated into Outlook, Word, Excel and PowerPoint.
Microsoft began rolling out a fix in early February 2026, tracked internally as service issue CW1226324.
Reported impact
The bug mainly impacted business and enterprise users of Microsoft 365 Copilot features at work.
Microsoft did not disclose how many customers were affected, whether email content was stored beyond generating summaries, or if the issue impacted all regions or only certain enterprise environments.
Index analysis
The bug bypassed data loss prevention controls intended to prevent automated ingestion of sensitive information into large language models.
Copilot Chat's deep integration with workplace data to provide context-aware responses created conditions where small bugs could raise serious privacy concerns.
Governance controls
Microsoft said admins can monitor the issue through its service dashboard.
The incident raised concerns about how AI tools handle sensitive workplace data, with some organizations already restricting built-in AI features on official devices over data security worries.
Classification
Sources and evidence
Sources not yet published
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