Security Resilience

CVE-2023-4474

RCE in Zyxel Nas326 Firmware ≤ 5.21\(aazf.14\)c0

RCECommand Injection
Published
30 November 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.30 98th percentile
Risk Priority 86 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-4474 is a critical-severity OS Command Injection (CWE-78) vulnerability in Zyxel Nas326 Firmware. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique NTDS (T1003.003); ranked in the top 2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-4474 is an OS command injection vulnerability (CWE-78) stemming from improper neutralization of special elements in the WSGI server component. It affects Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0, carrying a CVSS 3.1 base score of 9.8.

An unauthenticated remote attacker can exploit the flaw by submitting a crafted URL to a vulnerable device, resulting in arbitrary operating-system command execution with full impact on confidentiality, integrity, and availability.

Zyxel has published a security advisory covering authentication-bypass and command-injection issues in its NAS product line, alongside independent analysis from BugProve that details the affected firmware versions and exploitation vectors.

The EPSS score rose from a low baseline to a peak of 0.1628 (current value 0.1341), indicating emerging exploitation interest after public disclosure.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted URL to…

more

a vulnerable device.

CWE(s)
CWE-78

Related Threats

MITRE ATT&CK Enterprise Techniques

T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
attack.mitre.org →
T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
attack.mitre.org →
T1010 Application Window Discovery Discovery
Adversaries may attempt to get a listing of open application windows.
attack.mitre.org →
T1021.004 SSH Lateral Movement
Adversaries may use [Valid Accounts](https://attack.
attack.mitre.org →
T1021.008 Direct Cloud VM Connections Lateral Movement
Adversaries may leverage [Valid Accounts](https://attack.
attack.mitre.org →
T1027.001 Binary Padding Stealth
Adversaries may use binary padding to add junk data and change the on-disk representation of malware.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-37928Same product: Zyxel Nas326
CVE-2023-4473Same product: Zyxel Nas326
CVE-2024-29972Same product: Zyxel Nas326
CVE-2023-5372Same product: Zyxel Nas326
CVE-2023-37927Same product: Zyxel Nas326
CVE-2024-29973Same product: Zyxel Nas326
CVE-2024-6342Same product: Zyxel Nas326
CVE-2023-35138Same product: Zyxel Nas326
CVE-2023-27988Same product: Zyxel Nas326
CVE-2023-27992Same product: Zyxel Nas326

Affected Assets

zyxel
nas326 firmware
≤ 5.21\(aazf.14\)c0
zyxel
nas542 firmware
≤ 5.21\(abag.11\)c0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.5
  • V1.2.8

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-27 Platform-independent Applications
addresses: CWE-78

Platform-independent apps typically execute inside a managed runtime or sandbox that restricts direct OS command execution, reducing the ability to exploit OS command injection.

SI-10 Information Input Validation
addresses: CWE-78

Validates inputs to block special elements that would alter OS command execution.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
blocks

PR.PS-06's SDLC practices directly require secure coding and input handling that blocks command-injection defects, yet the single broad outcome leaves many specific neutralization vectors and verification gaps unaddressed.

PR.PS-02 partial match
blocks

Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

References