Critical severity · published Feb 10, 2026
CVE-2026-21531
Azure SDK for Python Remote Code Execution Vulnerability
9.8
CVSS
2.6%
EPSS
No
On KEV
Description
Deserialization of untrusted data in Azure SDK allows an unauthorized attacker to execute code over a network.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)2.6% · higher than 85% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AA
Azure AI Language Authoring · Microsoft
1.0.0 before 1.0.0b4 · source: vendor
AC
Azure Conversation Authoring Client Library · Microsoft
1.0.0; 1.0.0; 1.0.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-21531
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-21531
Vendor Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21531
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