CVE-2021-20038

SonicWall SMA 100 Appliances Stack-Based Buffer Overflow

9.8 CRITICALActively exploited (CISA KEV)Used in ransomwarePublic exploitEPSS 99.9%

Published8 Dec 2021
Added to CISA KEV28 Jan 2022
Remediation due11 Feb 2022

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 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected products

SonicWall Sma 200 Firmware10.2.0.8-37sv · 10.2.1.1-19sv · 10.2.1.2-24sv

SonicWall Sma 210 Firmware10.2.0.8-37sv · 10.2.1.1-19sv · 10.2.1.2-24sv

SonicWall Sma 400 Firmware10.2.0.8-37sv · 10.2.1.1-19sv · 10.2.1.2-24sv

SonicWall Sma 410 Firmware10.2.0.8-37sv · 10.2.1.1-19sv · 10.2.1.2-24sv

SonicWall Sma 500v Firmware10.2.0.8-37sv · 10.2.1.1-19sv · 10.2.1.2-24sv

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

Patch & vendor advisories

https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026

References

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

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2021-20038 being actively exploited?

Yes. CVE-2021-20038 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 28 Jan 2022. It has been used in ransomware campaigns.

How severe is CVE-2021-20038?

CVE-2021-20038 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 99.9% probability of exploitation.

Which products are affected by CVE-2021-20038?

Affected products include SonicWall Sma 200 Firmware, SonicWall Sma 210 Firmware, SonicWall Sma 400 Firmware, SonicWall Sma 410 Firmware, SonicWall Sma 500v Firmware.

How do I fix CVE-2021-20038?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-20038 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.