CVE-2021-20023 [Exploited] | Sonicwall EMAIL SECURITY Path Traversal

CVE-2021-20023 is rated Critical Active Threat (83.9/100): CVSS Medium severity, with high exploitation likelihood (EPSS 55.38%, 98th percentile). CISA KEV confirms active exploitation (added 2021-11-03) affecting SonicWall / SonicWall Email Security. a weakness (CWE-22) Unauthenticated remote administrative access may be possible. EPSS rose +12.70% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-09	42.68%	55.38%	+12.70%
2	2026-03-17	48.57%	42.68%	-5.89%
3	2026-02-22	—	48.57%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-09

42.68%

55.38%

+12.70%

2026-03-17

48.57%

42.68%

-5.89%

2026-02-22

—

48.57%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:H) They need powerful rights—admin, root, or similar—before this pays off. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	1.2	3.6	[email protected]
4.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:H) They need powerful rights—admin, root, or similar—before this pays off. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	1.2	3.6	134c704f-9b21-4f2e-91b3-4a467353bcc0
4.0	2.0	MEDIUM	`AV:N/AC:L/Au:S/C:P/I:N/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:N) No availability impact.	8.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.9

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H): They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

1.2

3.6

[email protected]

4.9

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H): They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

1.2

3.6

134c704f-9b21-4f2e-91b3-4a467353bcc0

4.0

2.0

MEDIUM

AV:N/AC:L/Au:S/C:P/I:N/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:N): No availability impact.

8.0

2.9

[email protected]

Affected software / configurations for CVE-2021-20023

Vendor	Product	Version	Raw CPE
sonicwall	email_security	< 10.0.9.6173	cpe:2.3:a:sonicwall:email_security::::::::
sonicwall	email_security_appliance_9000_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_9000_firmware::::::::
sonicwall	email_security_appliance_3300_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_3300_firmware::::::::
sonicwall	email_security_appliance_4300_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_4300_firmware::::::::
sonicwall	email_security_appliance_8300_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_8300_firmware::::::::
sonicwall	email_security_appliance_5000_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_5000_firmware::::::::
sonicwall	email_security_appliance_7000_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_7000_firmware::::::::
sonicwall	email_security_appliance_5050_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_5050_firmware::::::::
sonicwall	email_security_appliance_7050_firmware	< 10.0.9.6177	cpe:2.3:o:sonicwall:email_security_appliance_7050_firmware::::::::
sonicwall	email_security_virtual_appliance	< 10.0.9.6177	cpe:2.3:a:sonicwall:email_security_virtual_appliance::::::::
sonicwall	hosted_email_security	< 10.0.9.6173	cpe:2.3:a:sonicwall:hosted_email_security::::::::

References for CVE-2021-20023

URL	Tags
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0010	Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20023	US Government Resource

URL

CVE-2021-20023

CISA KEV Record for CVE-2021-20023

Exploit prediction scoring system (EPSS) score for CVE-2021-20023

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20023

Weakness enumeration for CVE-2021-20023

Affected software / configurations for CVE-2021-20023

References for CVE-2021-20023