Microsoft says bug causes Copilot to summarize confidential emails

Source: Bleeping Computer

Overview

Microsoft has identified a bug in Microsoft 365 Copilot that caused the AI assistant to summarize confidential emails stored in users’ Sent Items and Drafts folders. The issue bypassed data loss prevention (DLP) policies and sensitivity labels that are meant to restrict automated access to sensitive information.

Details of the Bug

• Service alert: The problem was first detected on January 21 and is tracked under CW1226324.
• Affected feature: The bug impacts the Copilot “work tab” chat, which incorrectly reads and summarizes emails that have confidentiality labels applied.
• Scope: Emails in Sent Items and Drafts with sensitivity labels and DLP policies were still processed by Copilot Chat.

“Users’ email messages with a confidential label applied are being incorrectly processed by Microsoft 365 Copilot chat,” Microsoft said when it confirmed this issue.

“The Microsoft 365 Copilot ‘work tab’ Chat is summarizing email messages even though these email messages have a sensitivity label applied and a DLP policy is configured.”

Copilot Chat Background

Microsoft 365 Copilot Chat is an AI‑powered, content‑aware chat feature that lets users interact with AI agents across Office apps. The rollout began in September 2025 for Word, Excel, PowerPoint, Outlook, and OneNote, targeting paying Microsoft 365 business customers.

Impact and Microsoft’s Response

• Root cause: An unspecified code error allowed items in Sent Items and Drafts to be picked up by Copilot despite confidential labels.
• Fix rollout: Microsoft began deploying a fix in early February and continues to monitor its deployment. As of the latest update, a subset of affected users is being contacted to verify the fix’s effectiveness.

“A code issue is allowing items in the sent items and draft folders to be picked up by Copilot even though confidential labels are set in place,” Microsoft added.

• Remediation timeline: No final timeline has been provided for full remediation, and Microsoft has not disclosed the number of affected users or organizations.
• Incident status: The incident is currently tagged as an advisory, indicating a limited‑scope service issue.

References

• Service alert: CW1226324
• Copilot Chat rollout announcement: BleepingComputer article