CVE-2021-20021

KEVRansomware UseSonicWall Email Security Improper Privilege Management Vulnerability

Description

SonicWall Email Security contains an improper privilege management vulnerability that allows an attacker to create an administrative account by sending a crafted HTTP request to the remote host. This vulnerability has known usage in a SonicWall Email Security exploit chain along with CVE-2021-20022 and CVE-2021-20023 to achieve privilege escalation.

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 3.1 vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

PublishedApr 9, 2021

Last modifiedAug 12, 2026

Added to KEVNov 3, 2021

Remediation dueNov 17, 2021

References

psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0007Vendor Advisory
cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20021US Government Resource

0 recent articles mention this CVE

Risk assessment · Critical

Actively exploited and used by ransomware crews. Patch immediately.

Exploitation: Confirmed in the wild (CISA KEV)
Federal remediation deadline: Overdue by 1806 days
Ransomware: Used in known ransomware campaigns
CVSS: 9.8 CRITICAL
EPSS (30-day exploit probability): 88.8% · top 1% of all CVEs
Weakness: CWE-269
Attack vector: Network, remotely reachable
Preconditions: No privileges and no user interaction

Recommended actions

1.Apply updates per vendor instructions.
2.Treat as emergency change: patch or isolate internet-facing instances first.
3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
5.Verify offline/immutable backups and segment the affected systems. This flaw is used for ransomware initial access.

Assessment is derived automatically from the live signals above; verify against your own asset inventory.