CVE-2026-26129Network attack vector

Unauthenticated information disclosure via command injection

Published May 7, 2026 · Updated May 7, 2026

Command injection in Microsoft 365 Copilot Chat allows remote attackers to disclose sensitive information over a network. Microsoft identifies improper neutralization of special command elements, but has not disclosed the affected command-processing locus or the crafted input that reaches it. No authentication or user interaction is required, and the documented consequence is limited to confidentiality loss in the Microsoft-hosted service.

CVSS severity7.5
High
EPSS probability1.14%
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 Chat allows remote attackers to disclose sensitive information over a network. Microsoft identifies improper neutralization of special command elements, but has not disclosed the affected command-processing locus or the crafted input that reaches it. No authentication or user interaction is required, and the documented consequence is limited to confidentiality loss in the Microsoft-hosted service.

The record

CVE
CVE-2026-26129
Published
May 7, 2026
Updated
May 7, 2026
Vendor
Microsoft
Product
Microsoft 365 Copilot Chat
Classifications
CWE-138, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. May 7, 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 Copilot Chatversion=-

Published CVSS scores

7.5Microsoft CorporationCVSS: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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-138Improper Neutralization of Special Elements
T1059Command and Scripting Interpreter

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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