Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2021-20038

SonicWall SMA100

SonicWall SMA100 · 10.2.0.8-37sv and earlier

Watch CVE-2021-20038 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
99.9%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-20038 is an unauthenticated vulnerability affecting SonicWall SMA100. A Stack-based buffer overflow vulnerability in SMA100 Apache httpd server's mod_cgi module environment variables allows a remote...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

SonicWall SMA100 10.2.0.8-37sv and earlier.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

SonicWall SMA100

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.

SonicWall Affected
SonicWall SMA100
10.2.0.8-37sv and earlier 10.2.1.1-19sv and earlier 10.2.1.2-24sv and earlier
Published
08 Dec 2021
Exploitation Reported
28 Jan 2022
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

malware nuclei_scanner cisa ransomware apache edge

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 28 Jan 2022

A trusted third party reported exploitation.

Used in malware

CISA

Recorded 28 Jan 2022

Malware families have been linked to exploitation of this CVE.

Proof of concept available

GitHub

Recorded 08 Aug 2022

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2022-01-28 00:00 UTC
Tenable Blog 2026-07-15 17:14 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-20038.yaml 25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

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

EPSS

99.9%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Stack-based Buffer Overflow CWE-121 Out-of-bounds Write CWE-787

Recent mention · Tenable Blog

CVE-2026-15409, CVE-2026-15410: SonicWall SMA 1000 zero-day vulnerabilities exploited in the wild

SonicWall patched two recently exploited zero-day vulnerabilities in its SMA 1000 Series secure remote access appliances which may have been chained for unauthenticated remote code execution.Key takeawaysCVE-2026-15409 and CVE-2026-15410 are a pair of exploited vulnerabilities...

Read full advisory

All CVSS Scores

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

CVSS v2.0 7.5 High

AV:N/AC:L/Au:N/C:P/I:P/A:P

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

SonicWall SMA100 Stack - Buffer Overflow/Remote Code Execution

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 17:14 UTC

    KEV confirmed by Tenable Blog

    Exploitation attested by an external source

  2. 14:20 UTC

    Public PoC available

    Public proof-of-concept code published

  3. 00:00 UTC

    Nuclei template available

    Scanner coverage available

  4. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. 00:00 UTC

    First public exploitation report

    Exploit observed in malware

  6. 09:55 UTC

    CVE published

    Vulnerability disclosed publicly

  7. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-20038

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2021-20038",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.99912,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}