Cyber Resilience

CVE-2023-6399

Zyxel Atp100 Firmware 5.10 – 5.37

Published
20 February 2024
Modified
21 January 2025
Patch / advisory
View advisory
CVSS Score v3.1 5.7
Click a component to see what it means
Raw vectorCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0065 48th percentile
Risk Priority 46 floored blend · peak EPSS

Summary

CVE-2023-6399 is a medium-severity Use of Externally-Controlled Format String (CWE-134) vulnerability in Zyxel Atp100 Firmware. Its CVSS base score is 5.7 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 48th percentile by exploit likelihood (below the median); 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.

EU & UK References

Vulnerability Data

A format string vulnerability 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 4.16 through 5.37 Patch 1, USG20(W)-VPN…

more

series firmware versions from 4.16 through 5.37 Patch 1, and USG FLEX H series firmware versions from 1.10 through 1.10 Patch 1 could allow an authenticated IPSec VPN user to cause DoS conditions against the “deviceid” daemon by sending a crafted hostname to an affected device if it has the “Device Insight” feature enabled.

CWE(s)
CWE-134NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-6764Same product: Zyxel Atp100
CVE-2023-33011Same product: Zyxel Usg Flex 100
CVE-2023-22923Same vendor: Zyxel
CVE-2023-22917Same product: Zyxel Atp100
CVE-2023-6397Same product: Zyxel Atp100
CVE-2023-33009Same product: Zyxel Atp100
CVE-2023-33010Same product: Zyxel Atp100
CVE-2023-22916Same product: Zyxel Atp100
CVE-2024-6343Same product: Zyxel Atp100
CVE-2023-4397Same product: Zyxel Atp100

Affected Assets

zyxel
atp100 firmware
5.37 · 5.10 — 5.37
zyxel
atp100w firmware
5.37 · 5.10 — 5.37
zyxel
atp200 firmware
5.37 · 5.10 — 5.37
zyxel
atp500 firmware
5.37 · 5.10 — 5.37
zyxel
atp700 firmware
5.37 · 5.10 — 5.37
zyxel
atp800 firmware
5.37 · 5.10 — 5.37
zyxel
usg flex 100 firmware
5.37 · 5.10 — 5.37
zyxel
usg flex 100ax firmware
5.37 · 5.10 — 5.37
zyxel
usg flex 100h firmware
5.37 · 5.10 — 5.37
zyxel
usg flex 100w firmware
5.37 · 5.10 — 5.37
+12 more product configuration(s) — see NVD for full list

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and static analysis can discover format-string vulnerabilities before deployment.

SI-10 Information Input Validation good match

Input validation can reject or sanitize externally supplied format strings before they reach formatting functions.

SA-15 Development Process, Standards, and Tools partial match

Secure development standards and tools can mandate use of static format strings or safe formatting APIs.

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
prevents

Secure SDLC practices directly prevent external format strings via code review, static analysis, and safe APIs.

ID.RA-01 partial match
prevents

Vulnerability identification can discover existing format-string flaws but does not prevent their introduction.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect format-string vulnerabilities before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates input validation and safe API usage that can prevent externally-controlled format strings.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify safe formatting functions and ban uncontrolled format strings.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles discourage dangerous string-handling patterns that lead to format-string issues.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly forbid the use of untrusted format strings and prescribe safe alternatives.

References