How severe is CVE-2021-42306?

CVE-2021-42306 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-42306 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42306?

CVE-2021-42306 primarily affects Microsoft Azure Active Directory. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-42306?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-42306 published?

CVE-2021-42306 was published on 2021-11-24 and last updated on 2026-06-17.

CVE-2021-42306

CVE-2021-42306 is a high-severity vulnerability in Microsoft Azure Active Directory with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-522.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 4.0
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-522
Affected product: Microsoft Azure Active Directory
Published: 2021-11-24
Last modified: 2026-06-17

Description

An information disclosure vulnerability manifests when a user or an application uploads unprotected private key data as part of an authentication certificate keyCredential  on an Azure AD Application or Service Principal (which is not recommended). This vulnerability allows a user or service in the tenant with application read access to read the private key data that was added to the application. Azure AD addressed this vulnerability by preventing disclosure of any private key values added to the application. Microsoft has identified services that could manifest this vulnerability, and steps that customers should take to be protected. Refer to the FAQ section for more information. For more details on this issue, please refer to the MSRC Blog Entry.

Frequently asked questions

What is CVE-2021-42306?: An information disclosure vulnerability manifests when a user or an application uploads unprotected private key data as part of an authentication certificate keyCredential  on an Azure AD Application or Service Principal (which is not recommended). This vulnerability allows a user or service in the tenant with application read access to read the private key data that was added to the application. Azure AD addressed this vulnerability by preventing disclosure of any private key values added to the application. Microsoft has identified services that could manifest this vulnerability, and steps that customers should take to be protected. Refer to the FAQ section for more information. For more details on this issue, please refer to the MSRC Blog Entry.
How severe is CVE-2021-42306?: CVE-2021-42306 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-42306 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42306?: CVE-2021-42306 primarily affects Microsoft Azure Active Directory. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-42306?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-42306 published?: CVE-2021-42306 was published on 2021-11-24 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42306

Affected products (4)

cpe:2.3:a:microsoft:azure_active_directory:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:azure_active_site_recovery:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:azure_automation:*:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:azure_migrate:*:*:*:*:*:*:*:*

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