CVE-2026-42824Public exploitNetwork attack vector

One-click data exfiltration via parameter-to-prompt injection

Published Jun 4, 2026 · Updated Jun 4, 2026

Command injection in Microsoft 365 Copilot allows remote attackers to disclose a signed-in user's work data through a crafted search link. Enterprise Search treats the URL q parameter as instructions, streams an attacker-supplied image before sanitization, and uses an allowlisted Bing image fetch to send indexed data to an attacker-controlled server. A signed-in enterprise user must click the link; exposure is limited to mailbox, calendar, SharePoint, OneDrive, and other indexed content available to that user.

CVSS severity6.5
Medium
EPSS probability7.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Microsoft 365 Copilot allows remote attackers to disclose a signed-in user's work data through a crafted search link. Enterprise Search treats the URL q parameter as instructions, streams an attacker-supplied image before sanitization, and uses an allowlisted Bing image fetch to send indexed data to an attacker-controlled server. A signed-in enterprise user must click the link; exposure is limited to mailbox, calendar, SharePoint, OneDrive, and other indexed content available to that user.

The record

CVE
CVE-2026-42824
Published
Jun 4, 2026
Updated
Jun 4, 2026
Vendor
Microsoft
Product
Microsoft 365 Copilot
Classifications
CWE-77, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=-

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft 365 Copilotversion=-

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
6.5Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1204.001User Execution: Malicious Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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