---
title: "CVE-2026-21531: Azure AI Language Authoring Elevation of Privilege Vulnerability can Lead to RCE"
url: https://erroneo.us/security/cve/CVE-2026-21531/
description: "CVE-2026-21531 (azure-ai-language-conversations-authoring (PyPI)): Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-10
date_modified: 2026-08-19
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-21531"
kev: false
cvss: 9.8
epss: 0.0258
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-21531: Azure AI Language Authoring Elevation of Privilege Vulnerability can Lead to RCE

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 2.6% , percentile 85: FIRST’s model estimates a 2.6% chance of exploitation activity in the next 30 days, higher than 85% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes azure-ai-language-conversations-authoring (PyPI) < 1.0.0b4, fixed in 1.0.0b4 . Check your lockfile, including transitive dependencies.

## What it is

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

## Affected packages

- PyPI `azure-ai-language-conversations-authoring` < 1.0.0b4 → fixed: 1.0.0b4

## Affected products (CVE record)

- Microsoft Azure AI Language Authoring: 1.0.0 < 1.0.0b4

## Severity

- microsoft CVSS 3.1: 9.8 `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`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 2.58% probability of exploitation activity in the next 30 days; percentile 85.

## Sources

- [Azure SDK for Python Remote Code Execution Vulnerability](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21531)
- [GitHub Advisory GHSA-436v-jg82-p533](https://github.com/advisories/GHSA-436v-jg82-p533)
- [CVE.org record CVE-2026-21531](https://www.cve.org/CVERecord?id=CVE-2026-21531)
- [NVD entry CVE-2026-21531](https://nvd.nist.gov/vuln/detail/CVE-2026-21531)

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Source page: https://erroneo.us/security/cve/CVE-2026-21531/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt