CVE-2022-0342 [Critical] | Authentication Bypass in Usg40 Firmware

An authentication bypass vulnerability in the CGI program of Zyxel USG/ZyWALL series firmware versions 4.20 through 4.70, USG FLEX series firmware versions 4.50 through 5.20, ATP series firmware versions 4.32 through 5.20, VPN series firmware versions 4.30 through 5.20, and NSG series firmware versions V1.20 through V1.33 Patch 4, which could allow an attacker to bypass the web authentication and obtain administrative access of the device.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-08	92.22%	92.36%	+0.14%
2	2026-03-19	92.56%	92.22%	-0.34%
3	2026-03-16	—	92.56%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-08

92.22%

92.36%

+0.14%

2026-03-19

92.56%

92.22%

-0.34%

2026-03-16

—

92.56%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` 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:N) No account or special rights needed—anonymous or random user is enough. 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:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` 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:N) No account or special rights needed—anonymous or random user is enough. 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:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
7.5	2.0	HIGH	`AV:N/AC:L/Au:N/C:P/I:P/A:P` 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:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	10.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 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:N): No account or special rights needed—anonymous or random user is enough.
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:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 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:N): No account or special rights needed—anonymous or random user is enough.
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:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

7.5

2.0

HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P 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:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

6.4

[email protected]

Affected software / configurations for CVE-2022-0342

Vendor	Product	Version	Raw CPE
zyxel	usg40_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:usg40_firmware::::::::
zyxel	usg40w_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:usg40w_firmware::::::::
zyxel	usg60_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:usg60_firmware::::::::
zyxel	usg60w_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:usg60w_firmware::::::::
zyxel	zywall_110_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:zywall_110_firmware::::::::
zyxel	zywall_310_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:zywall_310_firmware::::::::
zyxel	zywall_1100_firmware	>= 4.20, < 4.71	cpe:2.3:o:zyxel:zywall_1100_firmware::::::::
zyxel	usg_flex_100_firmware	>= 4.50, <= 5.20	cpe:2.3:o:zyxel:usg_flex_100_firmware::::::::
zyxel	usg_flex_200_firmware	>= 4.50, <= 5.20	cpe:2.3:o:zyxel:usg_flex_200_firmware::::::::
zyxel	usg_flex_500_firmware	>= 4.50, <= 5.20	cpe:2.3:o:zyxel:usg_flex_500_firmware::::::::
zyxel	usg_flex_100w_firmware	>= 4.50, <= 5.20	cpe:2.3:o:zyxel:usg_flex_100w_firmware::::::::
zyxel	usg_flex_700_firmware	>= 4.50, <= 5.20	cpe:2.3:o:zyxel:usg_flex_700_firmware::::::::
zyxel	atp100_firmware	>= 4.32, <= 5.20	cpe:2.3:o:zyxel:atp100_firmware::::::::
zyxel	atp100w_firmware	>= 4.32, <= 5.20	cpe:2.3:o:zyxel:atp100w_firmware::::::::
zyxel	atp200_firmware	>= 4.32, <= 5.20	cpe:2.3:o:zyxel:atp200_firmware::::::::
zyxel	atp500_firmware	>= 4.32, <= 5.20	cpe:2.3:o:zyxel:atp500_firmware::::::::
zyxel	atp700_firmware	>= 4.32, <= 5.20	cpe:2.3:o:zyxel:atp700_firmware::::::::
zyxel	atp800_firmware	>= 4.32, <= 5.20	cpe:2.3:o:zyxel:atp800_firmware::::::::
zyxel	vpn50_firmware	>= 4.30, < 5.21	cpe:2.3:o:zyxel:vpn50_firmware::::::::
zyxel	vpn100_firmware	>= 4.30, < 5.21	cpe:2.3:o:zyxel:vpn100_firmware::::::::
zyxel	vpn300_firmware	>= 4.30, < 5.21	cpe:2.3:o:zyxel:vpn300_firmware::::::::
zyxel	vpn1000_firmware	>= 4.30, < 5.21	cpe:2.3:o:zyxel:vpn1000_firmware::::::::
zyxel	nsg300_firmware	>= 1.20, < 1.33	cpe:2.3:o:zyxel:nsg300_firmware::::::::
zyxel	nsg300_firmware	1.33	cpe:2.3:o:zyxel:nsg300_firmware:1.33:-::::::
zyxel	nsg300_firmware	1.33	cpe:2.3:o:zyxel:nsg300_firmware:1.33:p4::::::

References for CVE-2022-0342

URL	Tags
https://www.zyxel.com/support/Zyxel-security-advisory-for-authentication-bypass-vulnerability-of-firewalls.shtml	Vendor Advisory

URL

CVE-2022-0342

Exploit prediction scoring system (EPSS) score for CVE-2022-0342

Common vulnerability scoring system (CVSS) metrics for CVE-2022-0342

Weakness enumeration for CVE-2022-0342

Affected software / configurations for CVE-2022-0342

References for CVE-2022-0342