How severe is CVE-2021-20040?

CVE-2021-20040 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-20040 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 26% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20040?

CVE-2021-20040 primarily affects Sonicwall Sma 200 Firmware. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20040?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-20040 published?

CVE-2021-20040 was published on 2021-12-08 and last updated on 2026-06-17.

CVE-2021-20040

CVE-2021-20040 is a high-severity vulnerability in Sonicwall Sma 200 Firmware with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 26% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-22.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 26% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-22
Affected product: Sonicwall Sma 200 Firmware
Published: 2021-12-08
Last modified: 2026-06-17

Description

A relative path traversal vulnerability in the SMA100 upload funtion allows a remote unauthenticated attacker to upload crafted web pages or files as a 'nobody' user. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances.

Frequently asked questions

What is CVE-2021-20040?: A relative path traversal vulnerability in the SMA100 upload funtion allows a remote unauthenticated attacker to upload crafted web pages or files as a 'nobody' user. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances.
How severe is CVE-2021-20040?: CVE-2021-20040 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-20040 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 26% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20040?: CVE-2021-20040 primarily affects Sonicwall Sma 200 Firmware. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20040?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-20040 published?: CVE-2021-20040 was published on 2021-12-08 and last updated on 2026-06-17.

References

https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0026

Affected products (10)

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_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_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_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_500v_firmware:10.2.0.8-37sv:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sma_500v_firmware:10.2.1.1-19sv:*:*:*:*:*:*:*

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