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
9.8
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 83%CVSS: 9.8Exploit: NoneExposed: 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
99.7%
KEV
⚠ Exploited

Published

April 9, 2021

Last Modified

November 10, 2025

Advisory Details (2)

Auto-updated Jun 1, 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 40× in last 7d / 193× 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 373 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 14:15 UTCEPSS rescore
  3. 2026-07-23 01:56 UTCEG score recompute
  4. 2026-07-22 21:43 UTCEG score recompute
  5. 2026-07-22 21:43 UTCGHSA enrichment
  6. 2026-07-22 19:40 UTCCISA KEV update
  7. 2026-07-22 17:13 UTCEG score recompute
  8. 2026-07-22 17:13 UTCGHSA enrichment
  9. 2026-07-22 14:05 UTCEPSS rescore
  10. 2026-07-22 12:56 UTCGHSA enrichment
  11. 2026-07-22 08:39 UTCGHSA enrichment
  12. 2026-07-22 04:22 UTCGHSA enrichment
  13. 2026-07-22 00:06 UTCGHSA enrichment
  14. 2026-07-21 18:06 UTCEG score recompute
  15. 2026-07-21 18:06 UTCGHSA enrichment
  16. 2026-07-21 15:22 UTCEPSS rescore
  17. 2026-07-21 15:22 UTCEPSS rescore
  18. 2026-07-21 14:37 UTCCISA KEV update
  19. 2026-07-21 13:48 UTCGHSA enrichment
  20. 2026-07-21 09:32 UTCGHSA enrichment
  21. 2026-07-21 05:15 UTCGHSA enrichment
  22. 2026-07-21 00:57 UTCGHSA enrichment
  23. 2026-07-20 20:40 UTCGHSA enrichment
  24. 2026-07-20 16:22 UTCGHSA enrichment
  25. 2026-07-20 12:06 UTCGHSA enrichment
Show 75 more
  1. 2026-07-20 07:49 UTCGHSA enrichment
  2. 2026-07-20 03:33 UTCGHSA enrichment
  3. 2026-07-19 23:16 UTCGHSA enrichment
  4. 2026-07-19 18:59 UTCGHSA enrichment
  5. 2026-07-19 14:43 UTCEG score recompute
  6. 2026-07-19 14:43 UTCGHSA enrichment
  7. 2026-07-19 14:28 UTCEPSS rescore
  8. 2026-07-19 10:27 UTCGHSA enrichment
  9. 2026-07-19 06:10 UTCGHSA enrichment
  10. 2026-07-19 01:53 UTCGHSA enrichment
  11. 2026-07-18 21:36 UTCGHSA enrichment
  12. 2026-07-18 17:19 UTCGHSA enrichment
  13. 2026-07-18 13:03 UTCGHSA enrichment
  14. 2026-07-18 08:47 UTCGHSA enrichment
  15. 2026-07-18 04:30 UTCGHSA enrichment
  16. 2026-07-18 00:13 UTCGHSA enrichment
  17. 2026-07-17 19:56 UTCGHSA enrichment
  18. 2026-07-17 15:40 UTCGHSA enrichment
  19. 2026-07-17 11:23 UTCGHSA enrichment
  20. 2026-07-17 07:06 UTCEG score recompute
  21. 2026-07-17 07:06 UTCGHSA enrichment
  22. 2026-07-17 02:50 UTCGHSA enrichment
  23. 2026-07-16 22:31 UTCGHSA enrichment
  24. 2026-07-16 18:14 UTCGHSA enrichment
  25. 2026-07-16 17:04 UTCCISA KEV update
  26. 2026-07-16 13:56 UTCGHSA enrichment
  27. 2026-07-16 09:40 UTCGHSA enrichment
  28. 2026-07-16 05:23 UTCGHSA enrichment
  29. 2026-07-16 01:07 UTCGHSA enrichment
  30. 2026-07-15 20:51 UTCGHSA enrichment
  31. 2026-07-15 16:55 UTCEPSS rescore
  32. 2026-07-15 16:55 UTCEPSS rescore
  33. 2026-07-15 16:49 UTCCISA KEV update
  34. 2026-07-15 16:33 UTCGHSA enrichment
  35. 2026-07-15 15:04 UTCCISA KEV update
  36. 2026-07-15 12:16 UTCGHSA enrichment
  37. 2026-07-15 07:57 UTCGHSA enrichment
  38. 2026-07-15 03:41 UTCGHSA enrichment
  39. 2026-07-14 23:23 UTCGHSA enrichment
  40. 2026-07-14 19:05 UTCGHSA enrichment
  41. 2026-07-14 18:05 UTCCISA KEV update
  42. 2026-07-14 14:47 UTCGHSA enrichment
  43. 2026-07-14 10:30 UTCGHSA enrichment
  44. 2026-07-14 06:14 UTCGHSA enrichment
  45. 2026-07-14 01:57 UTCGHSA enrichment
  46. 2026-07-13 21:41 UTCGHSA enrichment
  47. 2026-07-13 17:24 UTCGHSA enrichment
  48. 2026-07-13 17:07 UTCCISA KEV update
  49. 2026-07-13 13:07 UTCGHSA enrichment
  50. 2026-07-13 08:51 UTCGHSA enrichment
  51. 2026-07-13 06:10 UTCEPSS rescore
  52. 2026-07-13 06:10 UTCEPSS rescore
  53. 2026-07-13 04:35 UTCGHSA enrichment
  54. 2026-07-13 00:19 UTCGHSA enrichment
  55. 2026-07-12 20:02 UTCGHSA enrichment
  56. 2026-07-12 15:45 UTCGHSA enrichment
  57. 2026-07-12 11:29 UTCGHSA enrichment
  58. 2026-07-12 07:12 UTCGHSA enrichment
  59. 2026-07-12 02:56 UTCGHSA enrichment
  60. 2026-07-11 22:40 UTCGHSA enrichment
  61. 2026-07-11 18:24 UTCGHSA enrichment
  62. 2026-07-11 14:08 UTCGHSA enrichment
  63. 2026-07-11 09:49 UTCGHSA enrichment
  64. 2026-07-11 05:32 UTCGHSA enrichment
  65. 2026-07-11 01:15 UTCGHSA enrichment
  66. 2026-07-10 20:58 UTCGHSA enrichment
  67. 2026-07-10 17:52 UTCCISA KEV update
  68. 2026-07-10 16:42 UTCGHSA enrichment
  69. 2026-07-10 12:25 UTCGHSA enrichment
  70. 2026-07-10 08:09 UTCGHSA enrichment
  71. 2026-07-10 03:53 UTCGHSA enrichment
  72. 2026-07-09 23:36 UTCGHSA enrichment
  73. 2026-07-09 19:20 UTCGHSA enrichment
  74. 2026-07-09 19:07 UTCEPSS rescore
  75. 2026-07-09 15:03 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 November 10, 2025. 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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