CVE-2026-21531 Azure SDK for Python Remote Code Execution Vulnerability
An attacker can execute arbitrary code remotely by exploiting unsafe deserialization in the Azure AI Language Authoring SDK.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-21531?
CVE-2026-21531 is a critical unsafe deserialization vulnerability in Microsoft Azure AI Language Authoring, published on 10 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute code over a network.
Weakness: CWE-502
Which versions are affected by CVE-2026-21531?
3 open source packages ship an affected version, including azure-ai-language-conversations-authoring. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
azure-ai-language-conversations-authoring PyPI | All versions | 1.0.0b4 |
azure-ai-language-conversations-authoring PyPI | All versions | 1.0.0b4 |
azure-ai-language-conversations-authoring PyPI | All versions | 1.0.0b4 |
Products include Microsoft Azure Conversation Authoring Client Library.
How do I fix CVE-2026-21531?
Upgrade azure-ai-language-conversations-authoring to 1.0.0b4 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-21531 being exploited?
There is no known exploitation of CVE-2026-21531 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-436v-jg82-p533, PYSEC-2026-289.