What is the CVSS score of CVE-2021-20021?

CVE-2021-20021 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 83.4%.

Is there a public PoC exploit available for CVE-2021-20021?

Yes, a public proof-of-concept exploit is available for CVE-2021-20021. Prioritise patching immediately. EPSS: 83.4%.

Email Security Appliance 5000 Firmware CVE-2021-20021

CRITICAL

Improper Privilege Management (CWE-269)

2021-04-09 PSIRT@sonicwall.com

Privilege Escalation Sonicwall Email Security Appliance 5000 Firmware Email Security Appliance 5050 Firmware Email Security Appliance 7000 Firmware Email Security Appliance 7050 Firmware Email Security Appliance 9000 Firmware Email Security Email Security Virtual Appliance Email Security Appliance 3300 Firmware Email Security Appliance 4300 Firmware Email Security Appliance 8300 Firmware Hosted Email Security

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Jul 14, 2026 - 04:22 CISA

CVE Published

Apr 09, 2021 - 18:15 nvd

CRITICAL 9.8

DescriptionNVD

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.

AnalysisAI

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. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Technical ContextAI

This vulnerability is classified as Improper Privilege Management (CWE-269), which allows attackers to escalate privileges to gain unauthorized elevated access. 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 products include: Sonicwall Email Security, Sonicwall Email Security Appliance 9000 Firmware, Sonicwall Email Security Appliance 3300 Firmware, Sonicwall Email Security Appliance 4300 Firmware, Sonicwall Email Security Appliance 8300 Firmware. Version information: version 10.0.9..

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply principle of least privilege, validate privilege transitions, implement proper role separation.