Microsoft says bug causes Copilot to summarize confidential emails

Microsoft says a Microsoft 365 Copilot bug has been causing the AI assistant to summarize confidential emails since late January, bypassing data loss prevention (DLP) policies that organizations rely on to protect sensitive information.

According to a service alert seen by BleepingComputer, this bug (tracked under CW1226324 and first detected on January 21) affects the Copilot "work tab" chat feature, which incorrectly reads and summarizes emails stored in users' Sent Items and Drafts folders, including messages that carry confidentiality labels explicitly designed to restrict access by automated tools.

Copilot Chat (short for Microsoft 365 Copilot Chat) is the company's AI-powered, content-aware chat that lets users interact with AI agents. ​Microsoft began rolling out Copilot Chat to Word, Excel, PowerPoint, Outlook, and OneNote for paying Microsoft 365 business customers in September 2025.

"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."

Microsoft has since confirmed that an unspecified code error is responsible and said it began rolling out a fix in early February. As of Wednesday, the company said it was continuing to monitor the deployment and is reaching out to a subset of affected users to verify that the fix is working.

"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.

Microsoft has not provided a final timeline for full remediation and has not disclosed how many users or organizations were affected, saying only that the scope of impact may change as the investigation continues.

However, this ongoing incident has been tagged as an advisory, a flag commonly used to describe service issues typically involving limited scope or impact.

Update February 19, 12:17 EST: After the article was published, Microsoft reached out with a statement.

"We identified and addressed an issue where Microsoft 365 Copilot Chat could return content from emails labeled confidential authored by a user and stored within their Draft and Sent Items in Outlook desktop. This did not provide anyone access to information they weren’t already authorized to see," a Microsoft spokesperson told BleepingComputer.

"While our access controls and data protection policies remained intact, this behavior did not meet our intended Copilot experience, which is designed to exclude protected content from Copilot access. A configuration update has been deployed worldwide for enterprise customers."

Update February 20, 05:13 EST: Microsoft has updated the service alert, stating that the root cause behind this issue has been addressed. 

"Our targeted code fix to prevent further impact is moving forward and has saturated across the majority of affected environments. Our deployment remains in progress only for a small section of our more complex service environments," Microsoft noted. "As such, we believe the root cause of this issue has been addressed for most customers, and no new email messages for customers who have received the fix will be affected moving forward."