CVE-2026-21531: Azure ai language conversations authoring Remote Code Execution Vulnerability

CRITICAL
Advisory Identifier: GHSA-436v-jg82-p533
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CVSS 9.8
CWE-502
Published
Advisory Summary

CVE-2026-21531 is a CRITICAL (CVSS 9.8) remote code execution vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Azure ai language conversations authoring libraries in the PyPI ecosystem. The issue involves azure ai language authoring elevation of privilege vulnerability can lead to rce. Remediation is available by upgrading affected packages to version 1.0.0b4.

CVE-2026-21531 at a Glance

CVE Identifier CVE-2026-21531
GHSA Identifier GHSA-436v-jg82-p533
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Azure ai language conversations authoring
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 9.8

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
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-2026-21531

To remediate this vulnerability, upgrade all affected Azure ai language conversations authoring 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-ai-language-conversations-authoring fixed: 1.0.0b4 
pip install azure-ai-language-conversations-authoring>=1.0.0b4
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-ai-language-conversations-authoring

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-21531, inspect your installed packages using pip:

pip show azure-ai-language-conversations-authoring

Analyze the terminal output to locate any version of Azure ai language conversations authoring in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.0b4), your application is affected.

Note: The pip show azure-ai-language-conversations-authoring 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 ai language conversations authoring, 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 the Azure AI Language Conversations Authoring client library for Python allows an unauthorized attacker to execute code over a network.

CVE-2026-21531 Affected Azure ai language conversations authoring Versions

1 component(s)
Fixed Versions:
1.0.0b4
Product / Package Ecosystem Affected Versions Fixed Version
azure-ai-language-conversations-authoring
pypi/azure-ai-language-conversations-authoring
PyPI
< 1.0.0b4
1.0.0b4

References

NVD — CVE-2026-21531 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-21531
Azure ai language conversations authoring Source Repository REPOSITORY
https://github.com/Azure/azure-sdk-for-python
msrc.microsoft.com/update-guide/vulner... WEB
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21531

Frequently Asked Questions

What is CVE-2026-21531?
CVE-2026-21531 is a security vulnerability in Azure ai language conversations authoring involving Azure AI Language Authoring Elevation of Privilege Vulnerability can Lead to RCE under CWE-502: Deserialization of Untrusted Data.
Which Azure ai language conversations authoring versions are affected?
Affected versions include releases prior to 1.0.0b4 across affected packages: azure-ai-language-conversations-authoring.
What version fixes CVE-2026-21531?
Upgrading to 1.0.0b4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is azure-ai-language-conversations-authoring affected?
Yes, azure-ai-language-conversations-authoring is affected in releases prior to 1.0.0b4. Upgrade your dependency to 1.0.0b4 or later.
What is the CVSS score of CVE-2026-21531?
CVE-2026-21531 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-21531?
CVE-2026-21531 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-2026-21531?
Run the dependency tree command: 'pip show azure-ai-language-conversations-authoring'. 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-436v-jg82-p533",
  "modified" : "2026-02-12T19:19:53Z",
  "published" : "2026-02-10T18:30:42Z",
  "aliases" : [ "CVE-2026-21531" ],
  "summary" : "Azure AI Language Authoring Elevation of Privilege Vulnerability can Lead to RCE",
  "details" : "Deserialization of untrusted data in the Azure AI Language Conversations Authoring client library for Python allows an unauthorized attacker to execute code over a network.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "azure-ai-language-conversations-authoring"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.0b4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-21531"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Azure/azure-sdk-for-python"
  }, {
    "type" : "WEB",
    "url" : "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21531"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-12T18:28:29Z",
    "nvd_published_at" : "2026-02-10T18:16:35Z"
  }
}