Cyber Resilience

CVE-2021-20035

RCE in Sonicwall Sma 200 Firmware ≤ 9.0.0.11-31sv

CISA KEVActive ExploitationEUVD ExploitedRCECommand Injection
Published
27 September 2021
Modified
31 October 2025
KEV Added
16 April 2025
Patch / advisory
View advisory
CVSS Score v3.1 6.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.042 90th percentile
Risk Priority 76 floored blend · peak EPSS

Summary

CVE-2021-20035 is a medium-severity OS Command Injection (CWE-78) vulnerability in Sonicwall Sma 200 Firmware. Its CVSS base score is 6.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 10% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2021-20035 is an OS command injection vulnerability (CWE-78) stemming from improper neutralization of special elements in the management interface of SonicWall SMA 100 appliances. The flaw permits execution of arbitrary commands under the 'nobody' account and carries a CVSS 3.1 score of 6.5 reflecting network attack vector, low complexity, and high availability impact with no confidentiality or integrity effects.

A remote attacker who has already authenticated to the SMA 100 interface can exploit the weakness without user interaction to inject commands that result in denial of service. The attack requires only low-privileged credentials and does not need additional privileges or special network positioning beyond normal management access.

SonicWall advisory SNWLID-2021-0022 and the CISA Known Exploited Vulnerabilities catalog both reference the issue, confirming its inclusion in the CISA catalog of vulnerabilities observed in active exploitation.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

Improper neutralization of special elements in the SMA100 management interface allows a remote authenticated attacker to inject arbitrary commands as a 'nobody' user which potentially leads to DoS.

CWE(s)
CWE-78
KEV Date Added
16 April 2025

Related Threats

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1059.003 Windows Command Shell Execution
Adversaries may abuse the Windows command shell for execution.
attack.mitre.org →
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
attack.mitre.org →
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-44221Same product: Sonicwall Sma 200both on KEV
CVE-2021-20039Same product: Sonicwall Sma 200
CVE-2025-32821Same product: Sonicwall Sma 200
CVE-2021-20038Same product: Sonicwall Sma 200both on KEV
CVE-2021-20016Same product: Sonicwall Sma 200both on KEV
CVE-2021-20034Same product: Sonicwall Sma 200
CVE-2023-34127Same vendor: Sonicwall
CVE-2024-45318Same product: Sonicwall Sma 200
CVE-2024-40763Same product: Sonicwall Sma 200
CVE-2024-53703Same product: Sonicwall Sma 200

Affected Assets

sonicwall
sma 200 firmware
≤ 9.0.0.11-31sv · 10.2.0.0 — 10.2.0.8-37sv · 10.2.1.0 — 10.2.1.1-19sv
sonicwall
sma 210 firmware
≤ 9.0.0.11-31sv · 10.2.0.0 — 10.2.0.8-37sv · 10.2.1.0 — 10.2.1.1-19sv
sonicwall
sma 400 firmware
≤ 9.0.0.11-31sv · 10.2.0.0 — 10.2.0.8-37sv · 10.2.1.0 — 10.2.1.1-19sv
sonicwall
sma 410 firmware
≤ 9.0.0.11-31sv · 10.2.0.0 — 10.2.0.8-37sv · 10.2.1.0 — 10.2.1.1-19sv
sonicwall
sma 500v
≤ 9.0.0.11-31sv · 10.2.0.0 — 10.2.0.8-37sv · 10.2.1.0 — 10.2.1.1-19sv

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.5
  • V1.2.8
  • V15.2.5

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-27 Platform-independent Applications
addresses: CWE-78

Platform-independent apps typically execute inside a managed runtime or sandbox that restricts direct OS command execution, reducing the ability to exploit OS command injection.

SI-10 Information Input Validation
addresses: CWE-78

Validates inputs to block special elements that would alter OS command execution.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

PR.PS-06's SDLC practices directly require secure coding and input handling that blocks command-injection defects, yet the single broad outcome leaves many specific neutralization vectors and verification gaps unaddressed.

PR.PS-02 partial match
prevents

Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing and code review target insecure use of operating-system command interfaces, catching command-injection flaws introduced during development.

References