Security Resilience

CVE-2023-6398

RCE in Zyxel Atp100 Firmware 4.32 – 5.37

RCECommand Injection
Published
20 February 2024
Modified
21 January 2025
Patch / advisory
View advisory
CVSS Score v3.1 7.2
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.013 71th percentile
Risk Priority 55 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-2023-6398 is a high-severity OS Command Injection (CWE-78) vulnerability in Zyxel Atp100 Firmware. Its CVSS base score is 7.2 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique NTDS (T1003.003); ranked in the top 29% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

A post-authentication command injection vulnerability in the file upload binary in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from…

more

4.16 through 5.37 Patch 1, USG20(W)-VPN series firmware versions from 4.16 through 5.37 Patch 1, USG FLEX H series firmware versions from 1.10 through 1.10 Patch 1, NWA50AX firmware versions through 6.29(ABYW.3), WAC500 firmware versions through 6.65(ABVS.1), WAX300H firmware versions through 6.60(ACHF.1), and WBE660S firmware versions through 6.65(ACGG.1) could allow an authenticated attacker with administrator privileges to execute some operating system (OS) commands on an affected device via FTP.

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-2024-7261Same product: Zyxel Nwa110Ax
CVE-2023-27991Same product: Zyxel Atp100
CVE-2023-28771Same product: Zyxel Atp100
CVE-2022-30525Same product: Zyxel Atp100
CVE-2024-7203Same product: Zyxel Atp100
CVE-2024-42057Same product: Zyxel Atp100
CVE-2024-42059Same product: Zyxel Atp100
CVE-2024-42060Same product: Zyxel Atp100
CVE-2025-8078Same product: Zyxel Atp100
CVE-2023-34139Same product: Zyxel Usg Flex 100

Affected Assets

zyxel
atp100 firmware
5.37 · 4.32 — 5.37
zyxel
atp100w firmware
5.37 · 4.32 — 5.37
zyxel
atp200 firmware
5.37 · 4.32 — 5.37
zyxel
atp500 firmware
5.37 · 4.32 — 5.37
zyxel
atp700 firmware
5.37 · 4.32 — 5.37
zyxel
atp800 firmware
5.37 · 4.32 — 5.37
zyxel
usg flex 100 firmware
5.37 · 4.50 — 5.37
zyxel
usg flex 100ax firmware
5.37 · 4.50 — 5.37
zyxel
usg flex 100h firmware
5.37 · 4.50 — 5.37
zyxel
usg flex 100w firmware
5.37 · 4.50 — 5.37
+32 more product configuration(s) — see NVD for full list

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

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover missing or incorrect command sanitization during development.

SI-10 Information Input Validation good match

Input validation directly neutralizes or rejects special characters that would otherwise alter OS command structure.

AC-6 Least Privilege partial match

Least privilege reduces the permissions available to any process that could be subverted by injected commands.

CM-7 Least Functionality partial match

Least functionality restricts available OS commands and interpreters, limiting the blast radius of injection.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require proper neutralization of untrusted input before command construction.

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