Home/CVE/A command injection vulnerability in the web server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 fir
CVE

CVE-2023-4473

A command injection vulnerability in the web server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 fir

A command injection vulnerability in the web 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 a vulnerable device.

CRITICAL · CVSS 9.8 EPSS 0.3292
Schedule remediation
  • EPSS ≥ 0.10 - elevated exploitation probability
  • EPSS percentile: top 3% of all CVEs by exploitation likelihood
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

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

Affected Products & Versions

2
zyxel nas326 firmware<= 5.21\(aazf.14\)c0
zyxel nas542 firmware<= 5.21\(abag.11\)c0
◈

Detection Rules (IDS/IPS)

2
et-openET WEB_SPECIFIC_APPS Zyxel Authentication Bypass Attempt (CVE-2023-4473)attempted-admin
et-openET WEB_SPECIFIC_APPS Zyxel Authentication Bypass Attempt (CVE-2023-4473) - Information Leak via show_sysinfoattempted-admin
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 NVD30 Nov 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
poc
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.
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugprove.com/knowledge-hub/cve-2023-4473-and-cve-2023-4474-authentication-bypass-and-multiple-blind-os-command-injection-vulnerabilities-in-zyxel-s-nas-326-devices/
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-authentication-bypass-and-command-injection-vulnerabilities-in-nas-productsPatchVendor Advisory
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