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CVE-2021-20023

MEDIUM
4.9
CVSS Score
Published: April 20, 2021 at 11:55 AM UTC
Updated: October 1, 2026 at 09:17 PM UTC
19 products affected across 1 vendorEmail SecurityEmail Security Appliance 7050 FirmwareEmail Security Appliance 5000 Firmware· also runs on 1 platform

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Severity
MEDIUM4.9
Exploitation
CISA KEV
Exploit prediction
EPSS 52%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score51.7%

EPSS (Exploit Prediction Scoring System) estimates a 51.7% chance this CVE is exploited in the wild within the next 30 days — higher than 99% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

SonicWall Email Security contains a path traversal vulnerability that allows a post-authenticated attacker to read files on the remote host. This vulnerability has known usage in a SonicWall Email Security exploit chain along with CVE-2021-20021 and CVE-2021-20022 to achieve privilege escalation.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Known
Added to KEV
Nov 3, 2021
Remediation Due
Nov 17, 2021
1804 days overdue
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-20023

Description

SonicWall Email Security version 10.0.9.x contains a vulnerability that allows a post-authenticated attacker to read an arbitrary file on the remote host.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Email Security· SonicWall
95%
v ≤ 10.0.9v < 10.0.9.6173
Affected range stops below 10.0.9.6173, so it looks safe — our inference, not a vendor statement
microsoft-windows (environment)
Email Security Appliance 3300 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-3300 (same device)
Email Security Appliance 4300 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-4300 (same device)
Email Security Appliance 5000 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-5000 (same device)
Email Security Appliance 5050 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-5050 (same device)
Email Security Appliance 7000 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-7000 (same device)
Email Security Appliance 7050 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-7050 (same device)
Email Security Appliance 8300 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-8300 (same device)
Email Security Appliance 9000 Firmware· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement
sonicwall-email-security-appliance-9000 (same device)
Email Security Virtual Appliance· SonicWall
95%
v < 10.0.9.6177
Affected range stops below 10.0.9.6177, so it looks safe — our inference, not a vendor statement

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0010
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20023

SSVC — Action Prioritization

SSVCActiveAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.9MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-22

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