CVE-2022-40603Network attack vector

Browser information disclosure via reflected CGI payload

Published Dec 6, 2022 · Updated Apr 23, 2025

Reflected XSS in Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG firmware allows remote attackers to read browser data via a crafted URL. The CGI program incorporates an attacker-supplied URL payload into browser-rendered output without neutralizing executable script content. Exploitation requires a victim to visit the URL and execute the returned script, exposing browser-based information without reported device modification or service interruption.

CVSS severity4.7
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG firmware allows remote attackers to read browser data via a crafted URL. The CGI program incorporates an attacker-supplied URL payload into browser-rendered output without neutralizing executable script content. Exploitation requires a victim to visit the URL and execute the returned script, exposing browser-based information without reported device modification or service interruption.

The record

CVE
CVE-2022-40603
Published
Dec 6, 2022
Updated
Apr 23, 2025
Vendor
Zyxel Networks
Product
Zyxel ATP Series Firmware
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 6, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=4.32 through 5.31

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · Zyxel ATP Series Firmwareversion=4.32 through 5.31
Zyxel Networks · Zyxel ZyWALL/USG Series Firmwareversion=4.30 through 4.72
Zyxel Networks · Zyxel VPN Series Firmwareversion=4.30 through 5.31
Zyxel Networks · Zyxel USG FLEX Series Firmwareversion=4.50 through 5.31

Published CVSS scores

4.7Zyxel CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

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Your stack

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