CVE-2021-20038

CRITICAL9.8

CISA KEV

Published 2021-12-08 · Updated 2026-06-17 · Source PSIRT@sonicwall.com

Summary

CVE-2021-20038 is a critical-severity (CVSS 9.8) vulnerability in SonicWall SMA 100 Appliances. CISA added it to the Known Exploited Vulnerabilities catalog on January 28, 2022, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by February 11, 2022. CISA also lists it as known to be used in ransomware campaigns, so it should be prioritised accordingly. SonicWall has 19 vulnerabilities in the KEV catalog, 13 of them linked to ransomware.

All 19 known-exploited SonicWall vulnerabilities →

Description

A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote unauthenticated attacker to potentially execute code as a 'nobody' user in the appliance. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE-121CWE-787

CISA Known-Exploited Vulnerability

Product: SonicWall — SMA 100 Appliances

Name: SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability

Date added: 2022-01-28 · Due: 2022-02-11

USED IN RANSOMWARE

Required action: Apply updates per vendor instructions.

References

View on NVD

More exploited SonicWall vulnerabilities

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SMA1000 Appliances — SonicWall SMA1000 Appliances OS Command Injection Vulnerability
added 2026-09-02
CVE-2026-15409
RANSOMWARE
SMA1000 Appliances — SonicWall SMA1000 Appliances Server-Side Request Forgery Vulnerability
added 2026-07-14
CVE-2026-15410
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SMA1000 Appliances — SonicWall SMA1000 Appliances Code Injection Vulnerability
added 2026-07-14
CVE-2025-40602
SMA1000 appliance — SonicWall SMA1000 Missing Authorization Vulnerability
added 2025-12-17
CVE-2023-44221
SMA100 Appliances — SonicWall SMA100 Appliances OS Command Injection Vulnerability
added 2025-05-01

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