CVE-2022-0342Public exploitNetwork attack vector

Administrative access via non-GUI CGI authentication bypass

Published Mar 28, 2022 · Updated Aug 2, 2024

Authentication bypass in Zyxel firewall firmware allows remote attackers to gain administrative access through the web interface. The mod_auth_zyxel check_authtok path exempts CGI requests received on configured non-GUI Apache ports from authtok validation while cgi-bin remains globally exposed. Unauthenticated network access to an affected appliance listener is sufficient to read or alter device configuration with administrative privileges.

CVSS severity9.8
Critical
EPSS probability94.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authentication bypass in Zyxel firewall firmware allows remote attackers to gain administrative access through the web interface. The mod_auth_zyxel check_authtok path exempts CGI requests received on configured non-GUI Apache ports from authtok validation while cgi-bin remains globally exposed. Unauthenticated network access to an affected appliance listener is sufficient to read or alter device configuration with administrative privileges.

The record

CVE
CVE-2022-0342
Published
Mar 28, 2022
Updated
Aug 2, 2024
Vendor
Zyxel Networks
Product
Zyxel NSG Series Firmware
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.20 through 1.33 Patch 4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · Zyxel NSG Series Firmwareversion=1.20 through 1.33 Patch 4
Zyxel Networks · Zyxel ATP Series Firmwareversion=4.32 through 5.20
Zyxel Networks · Zyxel ZyWALL/USG Series Firmwareversion=4.20 through 4.70
Zyxel Networks · Zyxel VPN Series Firmwareversion=4.30 through 5.20
Zyxel Networks · Zyxel USG FLEX Series Firmwareversion=4.50 through 5.20

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8Zyxel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo