CVE-2026-42901Network attack vector

Unauthenticated privilege escalation via origin validation error

Published May 22, 2026 · Updated May 22, 2026

Origin validation error in Microsoft Entra ID allows remote attackers to elevate privileges through the hosted service. Microsoft has not disclosed which request origin is trusted incorrectly, which service locus performs the validation, or which privilege boundary the request crosses. No authentication or user interaction is required, and successful exploitation grants elevated privileges beyond the vulnerable service's security scope.

CVSS severity10.0
Critical
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation error in Microsoft Entra ID allows remote attackers to elevate privileges through the hosted service. Microsoft has not disclosed which request origin is trusted incorrectly, which service locus performs the validation, or which privilege boundary the request crosses. No authentication or user interaction is required, and successful exploitation grants elevated privileges beyond the vulnerable service's security scope.

The record

CVE
CVE-2026-42901
Published
May 22, 2026
Updated
May 22, 2026
Vendor
Microsoft
Product
Microsoft Entra ID
Classifications
CWE-346, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 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 Entra IDversion=-

Published CVSS scores

10.0Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

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.

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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-346Origin Validation Error
T1068Exploitation for Privilege Escalation

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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