Security Resilience

CVE-2023-28771

RCE in Zyxel Zywall Usg 310 Firmware 4.60 – 4.73

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRCECommand Injection
Published
25 April 2023
Modified
27 October 2025
KEV Added
31 May 2023
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 0.99 99.9th percentile
Risk Priority 97 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-2023-28771 is a critical-severity OS Command Injection (CWE-78) vulnerability in Zyxel Zywall Usg 310 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 0.1% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

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-2023-28771 is an improper error message handling flaw, tracked as CWE-78, that affects multiple Zyxel firewall product lines. Impacted devices include the ZyWALL/USG series running firmware 4.60 through 4.73, and the VPN, USG FLEX, and ATP series running firmware 4.60 through 5.35. The vulnerability permits unauthenticated remote code execution with a CVSS 3.1 score of 9.8.

An unauthenticated attacker can exploit the issue by sending specially crafted IKE packets to an exposed device, resulting in arbitrary OS command execution with full system privileges and no user interaction required.

Zyxel’s security advisory recommends immediate firmware upgrades to patched releases and, where upgrades are not feasible, applying the vendor-supplied workarounds. The flaw appears in CISA’s Known Exploited Vulnerabilities catalog, and its EPSS score has reached 0.9435, indicating active exploitation interest following disclosure.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an…

more

unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.

CWE(s)
CWE-78
KEV Date Added
31 May 2023

Related Threats

Threat-Actor AttributionAI

Google LLC (civil insider-recruitment defendant)
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
Lazarus Group (G0032)
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
AnonOps
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
Storm-0530
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
Maui ransomware
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA
l group
North Korea Cyber Group Conducts Global Espionage Campaign to Advance Regime’s Military and Nuclear Programs | CISA

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-2022-30525Same product: Zyxel Atp100both on KEV
CVE-2023-27991Same product: Zyxel Atp100
CVE-2020-9054Same product: Zyxel Atp100both on KEV
CVE-2017-6884Same vendor: Zyxelboth on KEV
CVE-2023-27992Same vendor: Zyxelboth on KEV
CVE-2024-40891Same vendor: Zyxelboth on KEV
CVE-2024-40890Same vendor: Zyxelboth on KEV
CVE-2024-7203Same product: Zyxel Atp100
CVE-2024-42060Same product: Zyxel Atp100
CVE-2024-42059Same product: Zyxel Atp100

Affected Assets

zyxel
atp100 firmware
4.60 — 5.36
zyxel
atp100w firmware
4.60 — 5.35
zyxel
atp200 firmware
4.60 — 5.36
zyxel
atp500 firmware
4.60 — 5.36
zyxel
atp700 firmware
4.60 — 5.36
zyxel
atp800 firmware
4.60 — 5.36
zyxel
usg flex 100 firmware
4.60 — 5.36
zyxel
usg flex 100w firmware
4.60 — 5.36
zyxel
usg flex 200 firmware
4.60 — 5.36
zyxel
usg flex 50 firmware
4.60 — 5.36
+9 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

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