Skip to main content
Varaxon Technologies

Known exploited vulnerability · CISA KEV

CVE-2021-20038: SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability

SonicWall SMA 100 devies are vulnerable to an unauthenticated stack-based buffer overflow vulnerability where exploitation can result in code execution.

CVE-2021-20038

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2022-01-28: attackers are using it right now. It is known to be used in ransomware campaigns.

CISA KEV
Listed
Added 2022-01-28 · federal fix-by 2022-02-11
EPSS (30 days)
100%
Higher than 99.9% of CVEs · 2026-11-01
CVSS v3.1
9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

What CISA says

SonicWall SMA 100 Appliances Stack-Based Buffer Overflow Vulnerability

Apply updates per vendor instructions.

NVD description · published 2021-12-08

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.

Full record on NVD

Got a whole scan? Scan Hub runs this check on every finding in your Nessus, Qualys, Rapid7 or OpenVAS export and ranks the report by it.

Try it free

How to check if you are exposed to CVE-2021-20038

  1. Find every SonicWall SMA 100 Appliances system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2021-20038.

US federal agencies had to fix this by 2022-02-11. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2021-20038. Check the vendor advisory for the exact fixed builds before you sign anything off.

ProductVulnerable versions
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 410 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 500v Firmware10.2.0.8-37sv; 10.2.1.1-19sv; 10.2.1.2-24sv

Timeline

  1. · Published in the National Vulnerability Database
  2. · Added to CISA's Known Exploited Vulnerabilities catalog, 51 days after it was published
  3. · Fix-by date for US federal agencies, passed 1,724 days ago

Weakness type

More exploited SonicWall vulnerabilities

CISA lists 19 exploited SonicWall vulnerabilities. The closest matches:

Keep going

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

Cookie preferences

Essential site functions remain available whichever option you choose. Your advertising choice is saved on this site. The Scan Hub has a separate choice.

Google and Reddit may receive cookies, identifiers, browser and device information, and your network/IP information. Reject or withdraw at any time. Read the Privacy Policy.