Microsoft has confirmed a significant security flaw in its Microsoft 365 Copilot Chat that allowed the AI to bypass strict data protection policies and summarize confidential emails for nearly a month.
The bug, tracked internally as CW1226324, highlights a critical “enforcement slip” in AI governance, exactly as global institutions like the European Parliament began sounding the alarm on AI data privacy.
Microsoft Copilot Confidential Email Bug CW1226324: Privacy Flaw Bypasses DLP Policies
Microsoft recently admitted to a “coding error” that effectively turned off the safety valves for its enterprise AI. Between January 21 and mid-February 2026, the Microsoft Copilot confidential email bug CW1226324 allowed Copilot Chat to read and summarize emails that were explicitly marked as “Confidential” and protected by Data Loss Prevention (DLP) policies.
Here is what enterprise admins and users need to know about the breach and the ongoing remediation.
1. How the Vulnerability Worked
The flaw resided in the “Work” tab of Copilot Chat. Under normal circumstances, Microsoft’s Purview Data Loss Prevention (DLP) should prevent Copilot from “ingesting” any content with a sensitivity label.
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The Glitch: A logic error allowed Copilot to pull data from two specific folders—Sent Items and Drafts—even when confidentiality labels were active.
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The Impact: Drafts often contain unredacted or raw information, while Sent Items hold finalized contracts and executive strategies. Copilot Chat was able to provide conversational summaries of this restricted data upon request.
2. European Parliament Responds with AI Ban
The timing of the Microsoft Copilot confidential email bug CW1226324 coincided with a major shift in EU policy.
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The Ban: On February 17, 2026, the European Parliament’s IT department disabled built-in AI features on all work-issued devices.
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The Reason: Lawmakers cited “unclarified data sharing” with cloud service providers. This bug serves as a “smoking gun” for those arguing that current AI safeguards are not yet robust enough for high-stakes governance.
3. Remediation and Current Status
Microsoft began deploying a server-side fix in early February 2026.
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Monitoring: As of February 18, Microsoft is still monitoring the deployment “saturation” and reaching out to a subset of affected tenants to verify the fix.
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Full Remediation: While the fix is rolling out, there is no public final timeline for when every single tenant will be 100% secure.
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Scope: Microsoft has not disclosed the total number of affected organizations, stating only that the “scope of impact may change” as the investigation continues.
4. Lessons for AI Governance
The Microsoft Copilot confidential email bug CW1226324 illustrates a fundamental risk in the SaaS-AI model:
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Enforcement Layers: A single code error can bypass years of established security (DLP) protocols.
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Shared Responsibility: Microsoft provides the tools, but companies must verify that those tools are actually honoring the “labels” they apply.
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The “Sent/Draft” Trap: Admins should prioritize auditing these folders, as they often bypass standard “read-only” scanning logic.
Conclusion: A Trust Deficit for Enterprise AI?
The Microsoft Copilot confidential email bug CW1226324 is a reminder that AI integration is currently moving faster than its security scaffolding. For organizations handling trade secrets or sensitive legal data, the “wait and see” approach adopted by the European Parliament may become the new standard for 2026.
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