CVE-2026-54130Network attack vector

Unauthenticated hosted information disclosure

Published Jun 18, 2026 · Updated Jun 18, 2026

Missing authentication in Microsoft 365 Copilot allows remote attackers to disclose hosted service information over a network. Microsoft has not published the affected function, request path, or omitted authentication check. No credentials or user interaction are required, but the disclosed consequence is limited to unspecified information exposure in Microsoft's hosted service.

CVSS severity9.8
Critical
EPSS probability1.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authentication in Microsoft 365 Copilot allows remote attackers to disclose hosted service information over a network. Microsoft has not published the affected function, request path, or omitted authentication check. No credentials or user interaction are required, but the disclosed consequence is limited to unspecified information exposure in Microsoft's hosted service.

The record

CVE
CVE-2026-54130
Published
Jun 18, 2026
Updated
Jun 18, 2026
Vendor
Microsoft
Product
Microsoft 365 Copilot
Classifications
CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 18, 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

9.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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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