AI Risk Wire

Cases › operational mistake › LR-2026-0447

Microsoft 365 Copilot bug raises data security concerns

Preliminary Why: 1 report: Fox News · subject to change · 1 independent report

Status: no action reported

Severity moderate
Reported 2 Mar 2026
Developer and model Microsoft

No source states: loss or records, agent tool, could do, deployer, industry.

Microsoft 365 Copilot Chat, an AI assistant used by business users, was found to be summarizing emails marked confidential. Beginning January 21, a coding error caused by internal bug CW1226324 led Copilot to read and summarize emails in the Sent Items and Drafts folders, and the issue bypassed Data Loss Prevention policies. Microsoft says the behaviour did not give anyone access to information they were not already authorised to see, and that its access controls remained intact. A fix began rolling out in early February, and a configuration update was deployed worldwide for enterprise customers. Microsoft has not provided a final remediation timeline or disclosed how many organisations were affected, and the issue was tagged as an advisory.

What happened

No source tells the story step by step yet.

What was done

No source states an action or fix.

Risks

Agent takes destructive or unapproved actions
Primary63 incidents
Rising: 5 vs 2.2 a week

Sorted by rule from the case's fields; not yet read from the sources.

Controls

Not yet read for controls. Controls that mitigate the primary risk:

Harness

Tool allow-list · Fail-closed defaults · Stop control

Application

Human approval for high-impact actions · Change review and separation of duties · Least-privilege access for the agent · Production kept apart from test · Activity logs · Adversarial testing before deployment

Infrastructure / target

Backups and recovery

Similar incidents

SearchLeak flaw in Microsoft 365 Copilot exposed data2026-06-15
EchoLeak zero-click prompt injection exploit in Microsoft 365 Copilot2025-11-23
Microsoft Copilot outage affects users in Europe2025-12-09
Reprompt: a single malicious Copilot link could expose user data2026-01-24

All cases of this kind ›

Evidence

No source states: a step-by-step account, when it happened, when it was found, how many records were exposed, the direct loss, a count of the other parties affected, any court case, the cause, what set it off, what was done.

Show the full account: 1 items from the primary sources

What happened, in order

  1. Jan. 21 Internal bug CW1226324 begins causing Copilot Chat to read and summarize confidential emails in Sent Items and Drafts folders.
Show every field, with its source and grade

The AI system

Developer
Microsoft
C one secondary source states it
What it was for
Helps business users summarize content, draft responses and analyze information across Word, Excel, PowerPoint, Outlook and OneNote
C one secondary source states it

What happened

Earliest source we hold
2026-03-02
D inferred by us from the described behaviour, reason shown
Cause in detail
A coding error in the Microsoft 365 Copilot Chat work tab feature
C one secondary source states it
Who was responsible
the model provider
C one secondary source states it
What went wrong
operational mistake
C one secondary source states it

Impact

Severity
moderate
D inferred by us from the described behaviour, reason shown

LR-2026-0447 · version 1 · published 2026-11-01 after automatic checks; not yet checked field by field by a person · JSON