Deserialization in Microsoft Azure Core Shared Client Library

CVE-2026-21226

Deserialization of untrusted data in Azure Core shared client library for Python allows an authorized attacker to execute code over a network.

Vulnerability class: Insecure Deserialization

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (59.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 59.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-21226: held from 0.008 to 0.009.

EPSS over last 30 days · oldest: 0.008 · newest: 0.009 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-21226?
CVE-2026-21226 is a high-severity vulnerability in Microsoft Azure Core Shared Client Library, classified under Deserialization of Untrusted Data. CVSS score: 7.5/10. Published 2026-01-13.
How severe is CVE-2026-21226?
High severity. CVSS v3 base score is 7.5 out of 10.