CVE-2026-21226: Azure core Azure Core Is Vulnerable To Vulnerability

HIGH
Advisory Identifier: GHSA-jm66-cg57-jjv5
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CVSS 7.5
CWE-502
Published
Advisory Summary

CVE-2026-21226 is a HIGH (CVSS 7.5) azure core is vulnerable to vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Azure core libraries in the PyPI ecosystem. The issue involves azure core is vulnerable to deserialization of untrusted data. Remediation is available by upgrading affected packages to version 1.38.0.

CVE-2026-21226 at a Glance

CVE Identifier CVE-2026-21226
GHSA Identifier GHSA-jm66-cg57-jjv5
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Azure core
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-21226

To remediate this vulnerability, upgrade all affected Azure core dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

azure-core fixed: 1.38.0 
pip install azure-core>=1.38.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show azure-core

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-21226, inspect your installed packages using pip:

pip show azure-core

Analyze the terminal output to locate any version of Azure core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.38.0), your application is affected.

Note: The pip show azure-core command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In Azure core, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Deserialization of untrusted data in Azure Core shared client library for Python allows an authorized attacker to execute code over a network.

CVE-2026-21226 Affected Azure core Versions

1 component(s)
Fixed Versions:
1.38.0
Product / Package Ecosystem Affected Versions Fixed Version
azure-core
pypi/azure-core
PyPI
< 1.38.0
1.38.0

References

NVD — CVE-2026-21226 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-21226
Azure core Source Repository REPOSITORY
https://github.com/Azure/azure-sdk-for-python
Azure core Source Repository REPOSITORY
https://github.com/Azure/azure-sdk-for-python/blob/6d2e6431ea0991861640e449e51e894247a7771a/sdk/core/azure-core/CHANGELOG.md#1380-2026-01-12
msrc.microsoft.com/update-guide/vulner... WEB
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21226

Frequently Asked Questions

What is CVE-2026-21226?
CVE-2026-21226 is a security vulnerability in Azure core involving Azure Core is vulnerable to deserialization of untrusted data under CWE-502: Deserialization of Untrusted Data.
Which Azure core versions are affected?
Affected versions include releases prior to 1.38.0 across affected packages: azure-core.
What version fixes CVE-2026-21226?
Upgrading to 1.38.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is azure-core affected?
Yes, azure-core is affected in releases prior to 1.38.0. Upgrade your dependency to 1.38.0 or later.
What is the CVSS score of CVE-2026-21226?
CVE-2026-21226 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-21226?
CVE-2026-21226 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check PyPI dependencies for CVE-2026-21226?
Run the dependency tree command: 'pip show azure-core'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jm66-cg57-jjv5",
  "modified" : "2026-01-13T21:57:47Z",
  "published" : "2026-01-13T21:31:44Z",
  "aliases" : [ "CVE-2026-21226" ],
  "summary" : "Azure Core is vulnerable to deserialization of untrusted data",
  "details" : "Deserialization of untrusted data in Azure Core shared client library for Python allows an authorized attacker to execute code over a network.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "azure-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.38.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-21226"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Azure/azure-sdk-for-python"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Azure/azure-sdk-for-python/blob/6d2e6431ea0991861640e449e51e894247a7771a/sdk/core/azure-core/CHANGELOG.md#1380-2026-01-12"
  }, {
    "type" : "WEB",
    "url" : "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21226"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-13T21:57:47Z",
    "nvd_published_at" : "2026-01-13T19:16:23Z"
  }
}