How severe is CVE-2021-20038?

CVE-2021-20038 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20038 being actively exploited?

Yes. CVE-2021-20038 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-01-28, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2021-20038?

CVE-2021-20038 primarily affects Sonicwall Sma 200 Firmware. In total, 15 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20038?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2021-20038 have an EU (EUVD) identifier?

Yes. CVE-2021-20038 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-7501. It is also flagged as exploited in the EUVD (since 2022-01-28).

When was CVE-2021-20038 published?

CVE-2021-20038 was published on 2021-12-08 and last updated on 2026-06-17.

CVE-2021-20038

CVE-2021-20038 is a critical-severity vulnerability in Sonicwall Sma 200 Firmware with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2022-01-28). The underlying weakness is classified as CWE-121.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 100% (100th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2022-01-28)
EU (EUVD) id: EUVD-2021-7501
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2022-01-28)
Weakness: CWE-121
Affected product: Sonicwall Sma 200 Firmware
Published: 2021-12-08
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-20038?: 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.
How severe is CVE-2021-20038?: CVE-2021-20038 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20038 being actively exploited?: Yes. CVE-2021-20038 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-01-28, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-20038?: CVE-2021-20038 primarily affects Sonicwall Sma 200 Firmware. In total, 15 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20038?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-20038 have an EU (EUVD) identifier?: Yes. CVE-2021-20038 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-7501. It is also flagged as exploited in the EUVD (since 2022-01-28).
When was CVE-2021-20038 published?: CVE-2021-20038 was published on 2021-12-08 and last updated on 2026-06-17.

References

Affected products (15)

cpe:2.3:o:sonicwall:sma_200_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_200_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_200_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_210_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_210_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_210_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_410_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_410_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_410_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_400_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_400_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_400_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.1.2-24sv:*:*:*:*:*:*:*

More vulnerabilities in Sonicwall Sma 200 Firmware

CVE-2022-22273 — Critical (CVSS 9.8): Improper neutralization of Special Elements leading to OS Command Injection vulnerability impacting end-of-life Secure…
CVE-2021-20045 — Critical (CVSS 9.8): A buffer overflow vulnerability in SMA100 sonicfiles RAC_COPY_TO (RacNumber 36) method allows a remote unauthenticated…
CVE-2021-20042 — Critical (CVSS 9.8): An unauthenticated remote attacker can use SMA 100 as an unintended proxy or intermediary undetectable proxy to bypass…
CVE-2021-20016 — Critical (CVSS 9.8): A SQL-Injection vulnerability in the SonicWall SSLVPN SMA100 product allows a remote unauthenticated attacker to…
CVE-2024-38475 — Critical (CVSS 9.1): Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to…
CVE-2021-20034 — Critical (CVSS 9.1): An improper access control vulnerability in SMA100 allows a remote unauthenticated attacker to bypass the path…

All CVEs affecting Sonicwall Sma 200 Firmware →

Other CWE-121 (Stack-based Buffer Overflow) vulnerabilities

CVE-2026-12848 — Critical (CVSS 10.0): GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and…
CVE-2026-12847 — Critical (CVSS 10.0): GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and…
CVE-2026-12846 — Critical (CVSS 10.0): GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and…
CVE-2026-12485 — Critical (CVSS 10.0): GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and…
CVE-2026-37541 — Critical (CVSS 10.0): Buffer overflow vulnerability in Open Vehicle Monitoring System 3 (OVMS3) 3.3.005. In canformat_gvret.cpp, the length…
CVE-2026-42996 — Critical (CVSS 10.0): JS8Call through 2.3.1 and JS8Call-improved before 3.0 have a stack-based buffer overflow via a radio transmission of…

Browse all CWE-121 (Stack-based Buffer Overflow) vulnerabilities →