CVE-2021-20021

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 4 sources updated this weekExploited in the wild
9.8EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 83%CVSS: 9.8Exploit: cisa kev · ssvc active · kev ransomware · epss top5pct · epss high · public exploitExposed: 0

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

A vulnerability in the SonicWall Email Security version 10.0.9.x allows an attacker to create an administrative account by sending a crafted HTTP request to the remote host.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
99(Act)
EG Risk 99/100SSVC: Act

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%
Exploitation100% × 40%
Automatability100% × 15%
Action: Fix now — active exploitation, automatable, high impact.
EPSS PROB
83%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

April 9, 2021

Last Modified

August 12, 2026

Advisory Details (2)

Auto-updated Sep 16, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20021
generic

Security Advisory

https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0007

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 51× in last 7d / 218× 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.

Showing the most recent 100 of 784 total refreshes for this CVE.

  1. 2026-09-20 23:54 UTCGHSA enrichment
  2. 2026-09-20 19:37 UTCGHSA enrichment
  3. 2026-09-20 15:20 UTCGHSA enrichment
  4. 2026-09-20 11:03 UTCGHSA enrichment
  5. 2026-09-20 06:45 UTCGHSA enrichment
  6. 2026-09-20 02:28 UTCGHSA enrichment
  7. 2026-09-19 22:12 UTCGHSA enrichment
  8. 2026-09-19 17:56 UTCGHSA enrichment
  9. 2026-09-19 13:40 UTCGHSA enrichment
  10. 2026-09-19 09:24 UTCGHSA enrichment
  11. 2026-09-19 05:04 UTCGHSA enrichment
  12. 2026-09-19 00:46 UTCGHSA enrichment
  13. 2026-09-18 20:30 UTCEG score recompute
  14. 2026-09-18 20:30 UTCGHSA enrichment
  15. 2026-09-18 19:23 UTCEPSS rescore
  16. 2026-09-18 19:20 UTCCISA KEV update
  17. 2026-09-18 16:14 UTCGHSA enrichment
  18. 2026-09-18 14:15 UTCCISA KEV update
  19. 2026-09-18 11:58 UTCGHSA enrichment
  20. 2026-09-18 07:42 UTCGHSA enrichment
  21. 2026-09-18 03:26 UTCGHSA enrichment
  22. 2026-09-17 23:10 UTCEG score recompute
  23. 2026-09-17 23:10 UTCGHSA enrichment
  24. 2026-09-17 19:23 UTCEPSS rescore
  25. 2026-09-17 18:53 UTCGHSA enrichment
Show 75 more
  1. 2026-09-17 14:34 UTCGHSA enrichment
  2. 2026-09-17 10:17 UTCGHSA enrichment
  3. 2026-09-17 06:01 UTCGHSA enrichment
  4. 2026-09-17 01:44 UTCGHSA enrichment
  5. 2026-09-16 21:28 UTCGHSA enrichment
  6. 2026-09-16 17:11 UTCEG score recompute
  7. 2026-09-16 17:11 UTCGHSA enrichment
  8. 2026-09-16 14:10 UTCCISA KEV update
  9. 2026-09-16 14:05 UTCEPSS rescore
  10. 2026-09-16 14:04 UTCEPSS rescore
  11. 2026-09-16 12:55 UTCGHSA enrichment
  12. 2026-09-16 08:38 UTCEG score recompute
  13. 2026-09-16 08:38 UTCGHSA enrichment
  14. 2026-09-16 04:21 UTCGHSA enrichment
  15. 2026-09-16 00:05 UTCGHSA enrichment
  16. 2026-09-15 19:48 UTCGHSA enrichment
  17. 2026-09-15 15:32 UTCGHSA enrichment
  18. 2026-09-15 11:16 UTCGHSA enrichment
  19. 2026-09-15 07:00 UTCGHSA enrichment
  20. 2026-09-15 02:43 UTCGHSA enrichment
  21. 2026-09-14 22:27 UTCGHSA enrichment
  22. 2026-09-14 19:24 UTCCISA KEV update
  23. 2026-09-14 18:10 UTCGHSA enrichment
  24. 2026-09-14 13:54 UTCGHSA enrichment
  25. 2026-09-14 09:37 UTCGHSA enrichment
  26. 2026-09-14 05:21 UTCGHSA enrichment
  27. 2026-09-14 01:05 UTCGHSA enrichment
  28. 2026-09-13 20:48 UTCGHSA enrichment
  29. 2026-09-13 16:31 UTCGHSA enrichment
  30. 2026-09-13 12:14 UTCGHSA enrichment
  31. 2026-09-13 07:57 UTCGHSA enrichment
  32. 2026-09-13 03:41 UTCGHSA enrichment
  33. 2026-09-12 23:24 UTCGHSA enrichment
  34. 2026-09-12 19:07 UTCGHSA enrichment
  35. 2026-09-12 14:51 UTCGHSA enrichment
  36. 2026-09-12 10:34 UTCGHSA enrichment
  37. 2026-09-12 06:18 UTCGHSA enrichment
  38. 2026-09-12 02:01 UTCGHSA enrichment
  39. 2026-09-11 21:44 UTCGHSA enrichment
  40. 2026-09-11 18:49 UTCCISA KEV update
  41. 2026-09-11 17:28 UTCEG score recompute
  42. 2026-09-11 17:28 UTCGHSA enrichment
  43. 2026-09-11 13:12 UTCGHSA enrichment
  44. 2026-09-11 08:56 UTCGHSA enrichment
  45. 2026-09-11 04:40 UTCGHSA enrichment
  46. 2026-09-11 00:24 UTCGHSA enrichment
  47. 2026-09-10 20:07 UTCGHSA enrichment
  48. 2026-09-10 19:28 UTCCISA KEV update
  49. 2026-09-10 15:50 UTCGHSA enrichment
  50. 2026-09-10 11:33 UTCEG score recompute
  51. 2026-09-10 11:33 UTCGHSA enrichment
  52. 2026-09-10 09:29 UTCEPSS rescore
  53. 2026-09-10 07:16 UTCGHSA enrichment
  54. 2026-09-10 03:00 UTCGHSA enrichment
  55. 2026-09-09 22:43 UTCGHSA enrichment
  56. 2026-09-09 19:08 UTCCISA KEV update
  57. 2026-09-09 18:27 UTCGHSA enrichment
  58. 2026-09-09 14:10 UTCGHSA enrichment
  59. 2026-09-09 09:54 UTCGHSA enrichment
  60. 2026-09-09 05:37 UTCGHSA enrichment
  61. 2026-09-09 01:21 UTCEG score recompute
  62. 2026-09-09 01:21 UTCGHSA enrichment
  63. 2026-09-08 21:56 UTCEPSS rescore
  64. 2026-09-08 21:05 UTCGHSA enrichment
  65. 2026-09-08 18:54 UTCCISA KEV update
  66. 2026-09-08 16:48 UTCGHSA enrichment
  67. 2026-09-08 12:30 UTCGHSA enrichment
  68. 2026-09-08 08:10 UTCGHSA enrichment
  69. 2026-09-08 03:53 UTCGHSA enrichment
  70. 2026-09-07 23:36 UTCGHSA enrichment
  71. 2026-09-07 19:20 UTCGHSA enrichment
  72. 2026-09-07 15:04 UTCGHSA enrichment
  73. 2026-09-07 10:47 UTCGHSA enrichment
  74. 2026-09-07 06:27 UTCGHSA enrichment
  75. 2026-09-07 02:07 UTCGHSA enrichment

Publicly available exploits

(2 references)

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

  • GitHub PoCSUPRAAA-1337/CVE-2021-20021
    First seen Sep 7, 2023
    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-20021.yaml
    First seen Jan 1, 2021

    SonicWall Email Security <= 10.0.9.x - Unauthenticated Admin Account Creation

    Open source ↗

Related CVEs(same CWE)

Frequently asked(6)

What is CVE-2021-20021?
CVE-2021-20021 is a critical vulnerability published on April 9, 2021. A vulnerability in the SonicWall Email Security version 10.0.9.x allows an attacker to create an administrative account by sending a crafted HTTP request to the remote host.
When was CVE-2021-20021 disclosed?
CVE-2021-20021 was first published in the National Vulnerability Database on April 9, 2021, with the most recent update on August 12, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-20021 actively exploited?
Yes. CISA added CVE-2021-20021 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting SonicWall SonicWall Email Security. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-20021?
CVE-2021-20021 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2021-20021?
CVE-2021-20021 affects SonicWall SonicWall Email Security. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-20021?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-20021, 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

Explore the affected products and dependency analysis for CVE-2021-20021

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