Home/CVE/Zyxel Multiple Firewalls OS Command Injection Vulnerability
CVE

CVE-2023-28771

Zyxel Multiple Firewalls OS Command Injection Vulnerability

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

CRITICAL · CVSS 9.8 ⚠ CISA KEV EPSS 0.94346
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 0% of all CVEs by exploitation likelihood
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

⬡

Weakness Classification

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
▤

Affected Products & Versions

21
zyxel atp100 firmware>= 4.60 and < 5.36
zyxel atp100w firmware>= 4.60 and < 5.35
zyxel atp200 firmware>= 4.60 and < 5.36
zyxel atp500 firmware>= 4.60 and < 5.36
zyxel atp700 firmware>= 4.60 and < 5.36
zyxel atp800 firmware>= 4.60 and < 5.36
zyxel usg flex 100 firmware>= 4.60 and < 5.36
zyxel usg flex 100w firmware>= 4.60 and < 5.36
⚠

Public Exploits & PoCs

2
nucleiUnauthenticated ZyXEL USG ZTP - Detecthigh
pocpacketstormsecurity.com · Zyxel-IKE-Packet-Decoder-Unauthenticated-Remote-Code-Exec...packetstormsecurity.com
◈

Detection Rules (IDS/IPS)

1
et-openET EXPLOIT Zyxel ZyWALL/USG OS Command Injection (CVE-2023-28771)web-application-attack
Open rulesets (ET Open, Snort Community, abuse.ch) link to source. Commercial rulesets are reference-only.
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · security@zyxel.com.tw
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD25 Apr 2023 · 02:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
yes
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
cisaKEV-CVE-2023-28771
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-28771US Government Resource
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