CVE-2021-42306: Azure Active Directory Information Disclosure Vulnerability

Severity: medium (CVSS 4.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-11-24 · updated 2026-08-19
Weakness: CWE-522

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.

Affected products

Microsoft Azure Active Directory: before 2021-10-30 — fixed in 2021-10-30
Microsoft Azure Active Site Recovery: before 2021-11-01 — fixed in 2021-11-01
Microsoft Azure Automation: before 2021-10-15 — fixed in 2021-10-15
Microsoft Azure Migrate: before 2021-11-02 — fixed in 2021-11-02
Microsoft Azure Active Directory: all versions
Microsoft Azure Automation: from 1.0.0 before publication — fixed in publication
Microsoft Azure Migrate: all versions
Microsoft Azure Site Recovery: all versions

How to fix

Upgrade to a fixed version: Microsoft Azure Active Directory 2021-10-30; Microsoft Azure Active Site Recovery 2021-11-01; Microsoft Azure Automation 2021-10-15; Microsoft Azure Migrate 2021-11-02; Microsoft Azure Automation publication. Check the vendor advisory for mitigations.

References

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