CVE-2026-21531: Azure SDK for Python Remote Code Execution Vulnerability

Overview

Severity

Critical (CVSS 9.8)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Category

Remote Code Execution

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Feb

Released

2026-02-10

EPSS Score

0.62% (percentile: 70.5%)

Description

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

FAQ

How could an attacker exploit this vulnerability? An attacker could supply a maliciously crafted continuation token that, when processed by the Azure AI Language Conversations Authoring SDK, triggers unsafe deserialization and executes attacker‑controlled code on the system using the SDK.

Affected Products (1)

Azure

• Azure AI Language Authoring

Security Updates (1)

• Release Notes

Acknowledgments

<a href="https://www.linkedin.com/in/muhammad-fadilullah-dzaki-a9080a2b5/">Muhammad Fadilullah Dzaki</a>

Revision History

• 2026-02-10: Information published.