What is CVE-2021-42311?

CVE-2021-42311 is a critical-severity vulnerability in Microsoft Defender For Iot, classified under SQL Injection. CVSS score: 10.0/10. Published 2021-12-15.

How severe is CVE-2021-42311?

Critical severity. CVSS v3 base score is 10.0 out of 10.

SQL Injection in Microsoft Defender For Iot

CVE-2021-42311

Microsoft Defender for IoT Remote Code Execution Vulnerability

Vulnerability class: SQL Injection

Published 2021-12-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.040 (90.3th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 90th percentile — 90.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.040 · newest: 0.040 · change: 0.000

Affected products

Microsoft Defender For Iot
Microsoft Defender For Iot — versions 22.0.0

Weakness classification (CWE)

CWE-89 — SQL Injection

References

portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42311 (Patch, Vendor Advisory)
www.zerodayinitiative.com/advisories/ZDI-21-1556/ (Exploit, VDB Entry, Third Party Advisory)

Frequently asked questions

What is CVE-2021-42311?: CVE-2021-42311 is a critical-severity vulnerability in Microsoft Defender For Iot, classified under SQL Injection. CVSS score: 10.0/10. Published 2021-12-15.
How severe is CVE-2021-42311?: Critical severity. CVSS v3 base score is 10.0 out of 10.