CVE-2021-20038

Name: CVE-2021-20038
Creator: NVD / NIST
Published: 2021-12-08T10:15:07.75+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10Actively ExploitedEPSS 99.91%

Last modified Jun 17, 2026

CVE-2021-20038 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. CISA has confirmed active exploitation in the wild. EPSS estimates a 99.91% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

99.91%

100.0th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Feb 11, 2022.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Sonicwall	Sma 200 Firmware	10.2.0.8-37sv
Sonicwall	Sma 200 Firmware	10.2.1.1-19sv
Sonicwall	Sma 200 Firmware	10.2.1.2-24sv
Sonicwall	Sma 210 Firmware	10.2.0.8-37sv
Sonicwall	Sma 210 Firmware	10.2.1.1-19sv
Sonicwall	Sma 210 Firmware	10.2.1.2-24sv
Sonicwall	Sma 410 Firmware	10.2.0.8-37sv
Sonicwall	Sma 410 Firmware	10.2.1.1-19sv
Sonicwall	Sma 410 Firmware	10.2.1.2-24sv
Sonicwall	Sma 400 Firmware	10.2.0.8-37sv
Sonicwall	Sma 400 Firmware	10.2.1.1-19sv
Sonicwall	Sma 400 Firmware	10.2.1.2-24sv
Sonicwall	Sma 500v Firmware	10.2.0.8-37sv
Sonicwall	Sma 500v Firmware	10.2.1.1-19sv
Sonicwall	Sma 500v Firmware	10.2.1.2-24sv

References

https://github.com/jbaines-r7/badbloodExploit, Third Party Advisory
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026Vendor Advisory
https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/Exploit, Third Party Advisory
https://github.com/jbaines-r7/badbloodExploit, Third Party Advisory
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026Vendor Advisory
https://www.rapid7.com/blog/post/2022/01/11/cve-2021-20038-42-sonicwall-sma-100-multiple-vulnerabilities-fixed-2/Exploit, Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20038US Government Resource

Timeline

Published: Dec 8, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-20038?

How severe is CVE-2021-20038?

CVE-2021-20038 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 99.91% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2021-20038?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20038?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST