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You trust your email security settings for a reason. So when an AI assistant quietly reads and summarizes messages marked confidential, that trust takes a hit.
Microsoft says a bug in Microsoft 365 Copilot allowed its AI chat feature to process sensitive emails since late January.
The issue bypassed Data Loss Prevention policies that organizations rely on to protect private information. Put simply, emails that were supposed to stay locked down were being summarized anyway.
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Microsoft 365 Copilot’s work chat interface sits at the center of the issue after a bug allowed it to summarize confidential emails. (Microsoft)
Microsoft 365 Copilot bug summarized confidential emails
Microsoft says a coding error impacted Microsoft 365 Copilot Chat, specifically the "work tab" feature. The AI assistant helps business users summarize content, draft responses and analyze information across Word, Excel, PowerPoint, Outlook and OneNote.
Beginning January 21, an internal bug labeled CW1226324 caused Copilot to read and summarize emails stored in Sent Items and Drafts folders.
The real concern runs deeper. Several of those messages carried confidentiality or sensitivity labels.
Companies apply those labels along with DLP policies to block automated systems from accessing restricted content. Despite those safeguards, Copilot still generated summaries.
We reached out to Microsoft, and a spokesperson provided CyberGuy with the following 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. 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."
Why the Microsoft 365 Copilot bug matters for data security
AI tools feel helpful. They save time and reduce busy work. But they also rely on deep access to your data. When safeguards fail, even temporarily, sensitive content can move in ways you did not expect.
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Legal discussions summarized outside intended controls
HR communications are exposed to automated analysis
Even if no data leaves the organization, the bypass itself raises concerns about how AI integrates with enterprise security systems.
Business users rely on Copilot to streamline work, but a recent bug raised concerns about how it handles sensitive email content. (Microsoft)
How Microsoft is fixing the Microsoft 365 Copilot bug
Microsoft says it began rolling out a fix in early February. The company continues to monitor deployment and is contacting some affected users to verify the fix works.
However, Microsoft has not provided a final timeline for full remediation. It has also not disclosed how many organizations were affected.
The issue is tagged as an advisory, which usually signals limited scope or impact. Still, many security professionals will want deeper clarity before feeling comfortable.
What this Microsoft 365 Copilot issue reveals about AI security
This incident highlights something many companies are wrestling with right now. AI assistants sit inside productivity platforms. They need access to email, documents and collaboration tools to work well.
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At the same time, those platforms contain your most sensitive information. When AI features expand quickly, security policies must evolve just as fast. Otherwise, even a small code mistake can create unexpected exposure.
The Copilot chat feature was designed to boost productivity, yet a code error let it process emails labeled confidential. (Microsoft)
Ways to stay safe after the Microsoft 365 Copilot bug
If your organization uses Microsoft 365 Copilot, here are practical steps to reduce risk:
Work with your IT team to confirm which folders and data sources Copilot can access.
Test sensitivity labels and DLP (Data Loss Prevention) rules to ensure they block AI processing as intended.
Stay current on Microsoft service alerts and verify that the fix is fully deployed in your tenant.
4) Limit AI scope during investigations
If you have concerns, consider temporarily restricting Copilot features until verification is complete.
5) Train employees on AI boundaries
Remind staff that AI assistants can process drafts and send messages. Encourage careful handling of sensitive content.
Review audit logs to see whether Copilot accessed or summarized labeled emails. This helps determine actual exposure rather than assumed risk.
Confirm that confidential labels are configured to block AI processing where required. Misconfigured labels can create gaps even after a bug is fixed.
