---
id: CVE-2021-20021
title: >-
  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.
summary: >-
  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.
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-269
  - CWE-269
vendor: sonicwall
product: email_security
affected:
  - email_security < 10.0.9.6103
  - email_security_appliance_9000_firmware < 10.0.9.6105
  - email_security_appliance_3300_firmware < 10.0.9.6105
  - email_security_appliance_4300_firmware < 10.0.9.6105
  - email_security_appliance_8300_firmware < 10.0.9.6105
  - email_security_appliance_5000_firmware < 10.0.9.6105
  - email_security_appliance_7000_firmware < 10.0.9.6105
  - email_security_appliance_5050_firmware < 10.0.9.6105
  - email_security_appliance_7050_firmware < 10.0.9.6105
  - email_security_virtual_appliance < 10.0.9.6105
  - hosted_email_security < 10.0.9.6103
patched:
  - email_security 10.0.9.6103
  - email_security_appliance_9000_firmware 10.0.9.6105
  - email_security_appliance_3300_firmware 10.0.9.6105
  - email_security_appliance_4300_firmware 10.0.9.6105
  - email_security_appliance_8300_firmware 10.0.9.6105
  - email_security_appliance_5000_firmware 10.0.9.6105
  - email_security_appliance_7000_firmware 10.0.9.6105
  - email_security_appliance_5050_firmware 10.0.9.6105
  - email_security_appliance_7050_firmware 10.0.9.6105
  - email_security_virtual_appliance 10.0.9.6105
  - hosted_email_security 10.0.9.6103
published: '2021-04-09'
updated: '2026-08-12'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-20021'
references:
  - url: 'https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0007'
    label: PSIRT@sonicwall.com
  - url: 'https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0007'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20021
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - kev
  - in-the-wild
  - exploit-available
epss: 0.8867
epssPercentile: 0.99771
kev: true
kevDateAdded: '2021-11-03'
kevDueDate: '2021-11-17'
kevRansomware: true
exploited: true
ingestedAt: '2026-08-12T19:54:25.883Z'
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/SUPRAAA-1337/CVE-2021-20021'
  nuclei:
    - CVE-2021-20021
  checkedAt: '2026-09-25T08:20:37.823Z'
exploitAvailable: true
---

## Overview

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.

## Affected

- `email_security < 10.0.9.6103`
- `email_security_appliance_9000_firmware < 10.0.9.6105`
- `email_security_appliance_3300_firmware < 10.0.9.6105`
- `email_security_appliance_4300_firmware < 10.0.9.6105`
- `email_security_appliance_8300_firmware < 10.0.9.6105`
- `email_security_appliance_5000_firmware < 10.0.9.6105`
- `email_security_appliance_7000_firmware < 10.0.9.6105`
- `email_security_appliance_5050_firmware < 10.0.9.6105`
- `email_security_appliance_7050_firmware < 10.0.9.6105`
- `email_security_virtual_appliance < 10.0.9.6105`
- `hosted_email_security < 10.0.9.6103`

## Remediation

Upgrade past the affected range:

- `email_security 10.0.9.6103`
- `email_security_appliance_9000_firmware 10.0.9.6105`
- `email_security_appliance_3300_firmware 10.0.9.6105`
- `email_security_appliance_4300_firmware 10.0.9.6105`
- `email_security_appliance_8300_firmware 10.0.9.6105`
- `email_security_appliance_5000_firmware 10.0.9.6105`
- `email_security_appliance_7000_firmware 10.0.9.6105`
- `email_security_appliance_5050_firmware 10.0.9.6105`
- `email_security_appliance_7050_firmware 10.0.9.6105`
- `email_security_virtual_appliance 10.0.9.6105`
- `hosted_email_security 10.0.9.6103`