CVE-2021-20021

CRITICALNVD 9.89.8—Trending — 4 sources updated this weekExploited in the wild

9.8

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)
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.

CWE-269Improper Privilege Management

Data Freshness Timeline

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

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-05 23:34 UTCEG score recompute
2026-06-05 23:34 UTCGHSA enrichment
2026-06-05 22:45 UTCepss_batch
2026-06-05 22:45 UTCepss_batch
2026-06-05 22:43 UTCkev_newly_listed
2026-06-05 19:18 UTCEG score recompute
2026-06-05 19:18 UTCGHSA enrichment
2026-06-05 15:02 UTCEG score recompute
2026-06-05 15:02 UTCGHSA enrichment
2026-06-05 10:45 UTCEG score recompute
2026-06-05 10:45 UTCGHSA enrichment
2026-06-05 06:29 UTCEG score recompute
2026-06-05 06:29 UTCGHSA enrichment
2026-06-05 06:09 UTCepss_batch
2026-06-05 06:09 UTCepss_batch
2026-06-05 06:08 UTCepss_batch
2026-06-05 02:13 UTCEG score recompute
2026-06-05 02:13 UTCGHSA enrichment
2026-06-04 21:57 UTCEG score recompute
2026-06-04 21:57 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 ↗

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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-20021

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Is Your Infrastructure Affected by CVE-2021-20021?

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CVE-2021-20021

📅 Published

🔄 Last Modified

📋 Advisory Details (2)