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Public proof of conceptFix available

CVE-2026-21531

Azure SDK for Python Remote Code Execution Vulnerability

A public proof of concept exists; no exploitation attested.

  • Published2026-02-10
  • WeaknessCWE-502

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute code over a network.

Timeline

dates in UTC
  1. 2026-02-1018:16CVE publishedNVD

Versions per branch

NVD · OSV
Microsoft azure conversation authoring client library
BranchAffectedFixed in
1.0= 1.0.0no fix published
azure-ai-language-conversations-authoring
BranchAffectedFixed in
1.0< 1.0.0b41.0.0b4

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As microsoft, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Microsoft Azure AI Language Authoring
    Affected
    • ≥ 1.0.0, < 1.0.0b4fixed in 1.0.0b4custom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-08-19

Fix

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2026-02-10
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-436v-jg82-p533

Frequently asked questions

What is CVE-2026-21531?

Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute code over a network.

Is CVE-2026-21531 actively exploited?

Active exploitation of CVE-2026-21531 has not been confirmed. Its EPSS score was 2.5% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-21531?

CVE-2026-21531 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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Sources for this record