CVE-2021-42306Network attack vector

Credential impersonation via readable cleartext private keys

Published Nov 24, 2021 · Updated Aug 19, 2026

Information disclosure in Microsoft Entra ID allows remote authenticated users to read cleartext application private keys through tenant APIs. The keyCredentials property accepted certificates containing private-key material, stored that material with application metadata, and returned it to any tenant principal with application-read access. Exposure requires a keyCredential containing a cleartext private key and enables impersonation of the affected application or service principal.

CVSS severity8.1
High
EPSS probability3.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Microsoft Entra ID allows remote authenticated users to read cleartext application private keys through tenant APIs. The keyCredentials property accepted certificates containing private-key material, stored that material with application metadata, and returned it to any tenant principal with application-read access. Exposure requires a keyCredential containing a cleartext private key and enables impersonation of the affected application or service principal.

The record

CVE
CVE-2021-42306
Published
Nov 24, 2021
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Microsoft Entra ID
Classifications
CWE-522, T1552.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 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 privilegesauthenticated

What is affected?

Microsoft · Microsoft Entra IDversion=-
Microsoft · Azure Migrateversion=-
Microsoft · Azure Automationversion=1.0.0 <publication
Microsoft · Azure Site Recoveryversion=-

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
8.1MicrosoftCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-522Insufficiently Protected Credentials
T1552.004Unsecured Credentials: Private Keys

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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