CVE-2021-20039

HIGHNVD 8.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 78% probability of exploitation within the next 30 days (top 0.5% of all CVEs). NVD baseline CVSS 8.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Weaponized
8.8
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 78%
CISA-KEV: Not listedEPSS: 78%CVSS: 8.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Improper neutralization of special elements in the SMA100 management interface '/cgi-bin/viewcert' POST http method allows a remote authenticated attacker to inject arbitrary commands as a 'nobody' user. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances.

CVSS v3
8.8
EG Score
9.0(high)
EG Risk
72(Track*)
EG Risk 72/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation78% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
99.5%
KEV
Not listed

Published

December 8, 2021

Last Modified

September 5, 2025

References (5)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 01:56 UTCEG score recompute▲ 0.20
  3. 2026-07-22 22:43 UTCEG score recompute
  4. 2026-07-22 14:05 UTCEPSS rescore
  5. 2026-07-21 15:22 UTCEPSS rescore
  6. 2026-07-21 15:22 UTCEPSS rescore
  7. 2026-07-16 17:00 UTCEPSS rescore
  8. 2026-07-15 16:55 UTCEPSS rescore
  9. 2026-07-15 16:55 UTCEPSS rescore
  10. 2026-07-13 22:27 UTCEPSS rescore
  11. 2026-07-13 22:27 UTCEPSS rescore
  12. 2026-07-11 08:25 UTCEPSS rescore
  13. 2026-07-05 02:28 UTCEPSS rescore
  14. 2026-07-05 02:28 UTCEPSS rescore
  15. 2026-07-02 16:57 UTCEPSS rescore
  16. 2026-07-01 15:03 UTCEPSS rescore
  17. 2026-06-27 03:06 UTCEPSS rescore
  18. 2026-06-27 03:06 UTCEPSS rescore
  19. 2026-06-25 13:48 UTCEPSS rescore
  20. 2026-06-25 13:48 UTCEPSS rescore
  21. 2026-06-23 21:31 UTCEPSS rescore
  22. 2026-06-23 21:31 UTCEPSS rescore
  23. 2026-06-17 17:51 UTCEPSS rescore
  24. 2026-06-16 17:50 UTCEPSS rescore
  25. 2026-06-15 17:46 UTCEPSS rescore
Show 24 more
  1. 2026-06-14 23:15 UTCEPSS rescore
  2. 2026-06-12 23:10 UTCEPSS rescore
  3. 2026-06-12 23:10 UTCEPSS rescore
  4. 2026-06-10 22:16 UTCEPSS rescore
  5. 2026-06-10 22:16 UTCEPSS rescore
  6. 2026-06-08 14:15 UTCEPSS rescore
  7. 2026-06-08 14:15 UTCEPSS rescore
  8. 2026-06-06 13:46 UTCEPSS rescore
  9. 2026-06-06 13:46 UTCEPSS rescore
  10. 2026-06-06 13:46 UTCEPSS rescore
  11. 2026-06-05 22:45 UTCEPSS rescore
  12. 2026-06-05 22:45 UTCEPSS rescore
  13. 2026-06-05 06:09 UTCEPSS rescore
  14. 2026-06-05 06:09 UTCEPSS rescore
  15. 2026-06-05 06:08 UTCEPSS rescore
  16. 2026-06-01 13:50 UTCEPSS rescore
  17. 2026-06-01 13:50 UTCEPSS rescore
  18. 2026-05-31 00:15 UTCEPSS rescore
  19. 2026-05-31 00:15 UTCEPSS rescore
  20. 2026-05-28 13:43 UTCEPSS rescore
  21. 2026-05-28 13:43 UTCEPSS rescore
  22. 2026-05-27 13:39 UTCEPSS rescore
  23. 2026-05-26 06:45 UTCEG score recompute
  24. 2026-05-26 06:45 UTCGHSA enrichment

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Metasploit module). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Metasploitexploit/linux/http/sonicwall_cve_2021_20039✓ verified
    First seen Dec 14, 2021

    SonicWall SMA 100 Series Authenticated Command Injection

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-20039?
CVE-2021-20039 is a high vulnerability published on December 8, 2021. Improper neutralization of special elements in the SMA100 management interface '/cgi-bin/viewcert' POST http method allows a remote authenticated attacker to inject arbitrary commands as a 'nobody' user. This vulnerability affected SMA 200, 210, 400, 410 and 500v appliances.
When was CVE-2021-20039 disclosed?
CVE-2021-20039 was first published in the National Vulnerability Database on December 8, 2021, with the most recent update on September 5, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-20039 actively exploited?
CVE-2021-20039 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-20039?
CVE-2021-20039 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2021-20039?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-20039, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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