CVE-2023-4474Network attack vector

Unauthenticated OS command execution via crafted URLs

Published Nov 30, 2023 · Updated Dec 16, 2025

OS command injection in Zyxel NAS326 5.21(AAZF.14)C0 and NAS542 5.21(ABAG.11)C0 allows remote attackers to execute OS commands. The WSGI server fails to neutralize special elements in crafted URL input, but Zyxel has not disclosed the affected handler or command construction. No credentials or user interaction are required, and the published impact is limited to execution of some operating system commands.

CVSS severity9.8
Critical
EPSS probability29.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Zyxel NAS326 5.21(AAZF.14)C0 and NAS542 5.21(ABAG.11)C0 allows remote attackers to execute OS commands. The WSGI server fails to neutralize special elements in crafted URL input, but Zyxel has not disclosed the affected handler or command construction. No credentials or user interaction are required, and the published impact is limited to execution of some operating system commands.

The record

CVE
CVE-2023-4474
Published
Nov 30, 2023
Updated
Dec 16, 2025
Vendor
Zyxel Networks
Product
NAS542 Firmware
Classifications
CWE-78, T1190, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 30, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 16, 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=5.21\(abag.11\)c0
  2. Affected versionversion=V5.21(ABAG.11)C0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · NAS542 Firmwareversion=5.21\(abag.11\)c0; version=V5.21(ABAG.11)C0
Zyxel Networks · NAS326 Firmwareversion=5.21\(aazf.14\)c0; version=V5.21(AAZF.14)C0

Published CVSS scores

9.8Zyxel CorporationCVSS: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1190Exploit Public-Facing Application
T1059Command and Scripting Interpreter

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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