What’s Vulnerable › Vulnerabilities

CVE-2022-0342

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 95.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-03-28 · updated 2026-06-17
• Weakness: CWE-287

Description

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.

Affected products

• Zyxel Atp100 Firmware: from 4.32 through 5.20
• Zyxel Atp100W Firmware: from 4.32 through 5.20
• Zyxel Atp200 Firmware: from 4.32 through 5.20
• Zyxel Atp500 Firmware: from 4.32 through 5.20
• Zyxel Atp700 Firmware: from 4.32 through 5.20
• Zyxel Atp800 Firmware: from 4.32 through 5.20
• Zyxel Nsg300 Firmware: from 1.20 before 1.33; 1.33, 1.33-p4 — fixed in 1.33
• Zyxel Usg40 Firmware: from 4.20 before 4.71 — fixed in 4.71
• Zyxel Usg40W Firmware: from 4.20 before 4.71 — fixed in 4.71
• Zyxel Usg60 Firmware: from 4.20 before 4.71 — fixed in 4.71
• Zyxel Usg60W Firmware: from 4.20 before 4.71 — fixed in 4.71
• Zyxel firewall (ZLD): from 4.50 through 5.20
• Zyxel USG FLEX 100(W) firmware: from 4.50 through 5.20
• Zyxel USG FLEX 200 firmware: from 4.50 through 5.20
• Zyxel USG FLEX 500 firmware: from 4.50 through 5.20
• Zyxel USG FLEX 700 firmware: from 4.50 through 5.20
• Zyxel Vpn1000 Firmware: from 4.30 before 5.21 — fixed in 5.21
• Zyxel Vpn100 Firmware: from 4.30 before 5.21 — fixed in 5.21
• Zyxel Vpn300 Firmware: from 4.30 before 5.21 — fixed in 5.21
• Zyxel Vpn50 Firmware: from 4.30 before 5.21 — fixed in 5.21
• Zyxel Zywall 1100 Firmware: from 4.20 before 4.71 — fixed in 4.71
• Zyxel Zywall 110 Firmware: from 4.20 before 4.71 — fixed in 4.71
• Zyxel Zywall 310 Firmware: from 4.20 before 4.71 — fixed in 4.71

How to fix

Upgrade to a fixed version: Zyxel Nsg300 Firmware 1.33; Zyxel Usg40 Firmware 4.71; Zyxel Usg40W Firmware 4.71; Zyxel Usg60 Firmware 4.71; Zyxel Usg60W Firmware 4.71; Zyxel Vpn1000 Firmware 5.21; Zyxel Vpn100 Firmware 5.21; Zyxel Vpn300 Firmware 5.21; Zyxel Vpn50 Firmware 5.21; Zyxel Zywall 1100 Firmware 4.71; Zyxel Zywall 110 Firmware 4.71; Zyxel Zywall 310 Firmware 4.71. Check the vendor advisory for mitigations.

References

• https://www.zyxel.com/support/Zyxel-security-advisory-for-authentication-bypass-vulnerability-of-firewalls.shtml
• https://www.zyxel.com/support/Zyxel-security-advisory-for-authentication-bypass-vulnerability-of-firewalls.shtml

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