Security Resilience

CVE-2021-20038

Memory Safety in Sonicwall Sma 200 Firmware 10.2.0.8-37sv … 10.2.1.2-24sv

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linkedMemory Safety
Published
08 December 2021
Modified
31 October 2025
KEV Added
28 January 2022
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.99 100.0th percentile
Risk Priority 97 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2021-20038 is a critical-severity Stack-based Buffer Overflow (CWE-121) vulnerability in Sonicwall Sma 200 Firmware. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Security Account Manager (T1003.002); ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

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

A stack-based buffer overflow vulnerability exists in the mod_cgi module of the Apache httpd server on SMA100 appliances, triggered via environment variables. It affects SonicWall SMA 200, 210, 400, 410, and 500v appliances running firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv, and earlier versions, and is also associated with CWE-121 and CWE-787.

A remote unauthenticated attacker can exploit the flaw over the network to potentially execute arbitrary code as the 'nobody' user on the appliance. The issue received a CVSS 3.1 score of 9.8, reflecting the combination of low attack complexity, no required privileges or user interaction, and full impact on confidentiality, integrity, and availability.

SonicWall PSIRT advisory SNWLID-2021-0026 and related reporting from Rapid7 document the issue, while public proof-of-concept code is available in the badblood repository.

EU & UK References

Vulnerability Data

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…

more

appliances firmware 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier versions.

CWE(s)
CWE-121CWE-787
KEV Date Added
28 January 2022

Related Threats

Threat-Actor AttributionAI

Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
2021 Top Routinely Exploited Vulnerabilities | CISA
AnonOps
2021 Top Routinely Exploited Vulnerabilities | CISA
HiddenTear
#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities | CISA
Storm-0530
#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities | CISA
Evil Ransomware
#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities | CISA
Maui ransomware
#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities | CISA
red ransomware
#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities | CISA
eCh0raix
#StopRansomware: Ransomware Attacks on Critical Infrastructure Fund DPRK Malicious Cyber Activities | CISA
Google LLC (civil insider-recruitment defendant)
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
Lazarus Group (G0032)
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
l group
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA

MITRE ATT&CK Enterprise Techniques

T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
attack.mitre.org →
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
T1003.008 /etc/passwd and /etc/shadow Credential Access
Adversaries may attempt to dump the contents of <code>/etc/passwd</code> and <code>/etc/shadow</code> to enable offline password cracking.
attack.mitre.org →
T1006 Direct Volume Access Stealth
Adversaries may directly access a volume to bypass file access controls and file system monitoring.
attack.mitre.org →
T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-6340Same vendor: Sonicwall
CVE-2023-39278Same vendor: Sonicwall
CVE-2023-41712Same vendor: Sonicwall
CVE-2023-41711Same vendor: Sonicwall
CVE-2022-22274Same vendor: Sonicwall
CVE-2023-0656Same vendor: Sonicwall
CVE-2023-39279Same vendor: Sonicwall
CVE-2023-39277Same vendor: Sonicwall
CVE-2024-29012Same vendor: Sonicwall
CVE-2023-39280Same vendor: Sonicwall

Affected Assets

sonicwall
sma 200 firmware
10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
sonicwall
sma 210 firmware
10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
sonicwall
sma 410 firmware
10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
sonicwall
sma 400 firmware
10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv
sonicwall
sma 500v firmware
10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 2 hardening rules · 2 OS baselines
Validate
Prove the fix (OWASP ASVS)

—

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.

SI-16 Memory Protection
addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

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.

ID.RA-01 partial match
blocks

Vulnerability scanning can discover stack buffer overflows but does not prevent their introduction.

PR.PS-02 partial match
blocks

Patching eliminates known instances of the weakness after discovery.

PR.PS-06 partial match
blocks

Secure-development practices directly prevent introduction of stack buffer overflows.

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.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.7.2 Physical entry partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248594 OL 8 must implement address space layout randomization (ASLR) to protect its memory from unauthorized code execution. blocks CWE-121
Oracle Linux 9 (1 rule)
  • V-271452 OL 9 must use a Linux Security Module configured to enforce limits on system services. blocks CWE-121

References