CVE-2021-4039

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-03-02. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
9.8
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 71%
CISA-KEV: Not listedEPSS: 71%CVSS: 9.8Exploit: NoneExposed: 0

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

A command injection vulnerability in the web interface of the Zyxel NWA-1100-NH firmware could allow an attacker to execute arbitrary OS commands on the device.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
77(Track*)
EG Risk 77/100SSVC: 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
Severity98% × 45%
Exploitation71% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
99.3%
KEV
Not listed

Published

March 1, 2022

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated May 26, 2026
No patch confirmed yet.
generic

Support Download Page Redirect

https://www.zyxel.com/support/OS-command-injection-vulnerability-of-NWA1100-NH-access-point.shtml
generic

Packet Storm

http://packetstormsecurity.com/files/166752/Zyxel-NWA-1100-NH-Command-Injection.html

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 23× 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. 2026-07-24 14:15 UTCEPSS rescore
  3. 2026-07-23 02:04 UTCEG score recompute
  4. 2026-07-22 22:50 UTCEG score recompute
  5. 2026-07-22 14:06 UTCEPSS rescore
  6. 2026-07-20 17:05 UTCEPSS rescore
  7. 2026-07-19 14:29 UTCEPSS rescore
  8. 2026-07-19 02:27 UTCEPSS rescore
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  10. 2026-07-15 16:55 UTCEPSS rescore
  11. 2026-07-13 06:11 UTCEPSS rescore
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  13. 2026-07-12 05:44 UTCEPSS rescore
  14. 2026-07-09 19:07 UTCEPSS rescore
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  16. 2026-07-04 06:29 UTCEPSS rescore
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  18. 2026-07-01 15:04 UTCEPSS rescore
  19. 2026-06-30 23:20 UTCEPSS rescore
  20. 2026-06-27 03:07 UTCEPSS rescore
  21. 2026-06-27 03:06 UTCEPSS rescore
  22. 2026-06-25 13:48 UTCEPSS rescore
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  24. 2026-06-24 14:03 UTCEPSS rescore
  25. 2026-06-24 14:03 UTCEPSS rescore
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  1. 2026-06-23 21:31 UTCEPSS rescore
  2. 2026-06-23 21:31 UTCEPSS rescore
  3. 2026-06-21 01:58 UTCEPSS rescore
  4. 2026-06-21 01:58 UTCEPSS rescore
  5. 2026-06-18 17:51 UTCEPSS rescore
  6. 2026-06-18 17:51 UTCEPSS rescore
  7. 2026-06-17 17:51 UTCEPSS rescore
  8. 2026-06-17 17:51 UTCEPSS rescore
  9. 2026-06-15 17:46 UTCEPSS rescore
  10. 2026-06-14 23:15 UTCEPSS rescore
  11. 2026-06-14 23:15 UTCEPSS rescore
  12. 2026-06-13 22:58 UTCEPSS rescore
  13. 2026-06-13 22:58 UTCEPSS rescore
  14. 2026-06-12 23:10 UTCEPSS rescore
  15. 2026-06-11 13:58 UTCEPSS rescore
  16. 2026-06-10 22:16 UTCEPSS rescore
  17. 2026-06-10 13:20 UTCEPSS rescore
  18. 2026-06-07 15:23 UTCEPSS rescore
  19. 2026-06-07 15:23 UTCEPSS rescore
  20. 2026-06-05 22:45 UTCEPSS rescore
  21. 2026-06-05 22:45 UTCEPSS rescore
  22. 2026-06-05 06:09 UTCEPSS rescore
  23. 2026-06-05 06:09 UTCEPSS rescore
  24. 2026-06-02 20:11 UTCEPSS rescore
  25. 2026-06-02 20:11 UTCEPSS rescore
  26. 2026-06-01 13:50 UTCEPSS rescore
  27. 2026-06-01 13:50 UTCEPSS rescore
  28. 2026-05-31 00:15 UTCEPSS rescore
  29. 2026-05-31 00:15 UTCEPSS rescore
  30. 2026-05-29 13:42 UTCEPSS rescore
  31. 2026-05-26 02:19 UTCEG score recompute
  32. 2026-05-26 02:19 UTCGHSA enrichment

Publicly available exploits

(1 reference)

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

  • Exploit-DBEDB-50870
    First seen Apr 19, 2022

    Zyxel NWA-1100-NH - Command Injection

    Open source ↗

Frequently asked(5)

What is CVE-2021-4039?
CVE-2021-4039 is a critical vulnerability published on March 1, 2022. A command injection vulnerability in the web interface of the Zyxel NWA-1100-NH firmware could allow an attacker to execute arbitrary OS commands on the device.
When was CVE-2021-4039 disclosed?
CVE-2021-4039 was first published in the National Vulnerability Database on March 1, 2022, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-4039 actively exploited?
CVE-2021-4039 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-4039?
CVE-2021-4039 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-4039?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-4039, 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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