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Nas326 Firmware CVE-2024-29974

CRITICAL
Unrestricted Upload of File with Dangerous Type (CWE-434)
2024-06-04 security@zyxel.com.tw
9.8
CVSS 3.1 · Vendor: zyxel
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK

2 techniques across 2 tactics: Command and Control, Persistence

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

A remote attacker could upload malicious files that can be executed on the server by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

Act Now Prioritize within 24-48h. Why: CRITICAL + active threat signals, no patch available.
No patch listed yet 22.8% exploitation probability (EPSS)

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AnalysisAI

UNSUPPORTED WHEN ASSIGNED The remote code execution vulnerability in the CGI program “file_upload-cgi” in Zyxel NAS326 firmware versions before V5.21(AAZF.17)C0 and NAS542 firmware versions. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate file types server-side, store uploads outside webroot, use random filenames, scan for malware.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Unrestricted File Upload (CWE-434), which allows attackers to upload malicious files that can be executed on the server. UNSUPPORTED WHEN ASSIGNED The remote code execution vulnerability in the CGI program “file_upload-cgi” in Zyxel NAS326 firmware versions before V5.21(AAZF.17)C0 and NAS542 firmware versions before V5.21(ABAG.14)C0 could allow an unauthenticated attacker to execute arbitrary code by uploading a crafted configuration file to a vulnerable device. Affected products include: Zyxel Nas326 Firmware, Zyxel Nas542 Firmware.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (zyxel) PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from Vendor (zyxel) · only source for this CVE.

CVSS VectorVendor: zyxel

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

UNSUPPORTED WHEN ASSIGNED The remote code execution vulnerability in the CGI program “file_upload-cgi” in Zyxel NAS326 firmware versions before V5.21(AAZF.17)C0 and NAS542 firmware versions before V5.21(ABAG.14)C0 could allow an unauthenticated attacker to execute arbitrary code by uploading a crafted configuration file to a vulnerable device.

Threat Intelligence Overview

EPSS Score
22.8%
Top 3% exploitable
Exploit
POC
Public exploit code exists
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC Yes
EPSS 22.8%
Patch available No
Active threat Yes
Deciding rule
CRITICAL + active threat signals, no patch available
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

92
Low Medium High Critical
KEV: 0
EPSS: +23
CVSS: +49
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)CVE.org

cpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*
CVE-2020-9054 CRITICAL POC
9.8 Mar 04

Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command

CVE-2024-29973 CRITICAL POC
9.8 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the “setCookie” parameter in Zyxel NAS326 firmwar

CVE-2024-29972 CRITICAL POC
9.8 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the CGI program "remote_help-cgi" in Zyxel NAS326

CVE-2019-10633 HIGH POC
8.8 Apr 09

An eval injection vulnerability in the Python web server routing on the Zyxel NAS 326 version 5.21 and below allows a re

CVE-2019-10631 HIGH POC
8.8 Apr 09

Shell Metacharacter Injection in the package installer on Zyxel NAS 326 version 5.21 and below allows an authenticated a

CVE-2019-10630 HIGH POC
8.8 Apr 09

A plaintext password vulnerability in the Zyxel NAS 326 through 5.21 allows an elevated privileged user to get the admin

CVE-2024-29975 MEDIUM POC
6.7 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The improper privilege management vulnerability in the SUID executable binary in Zyxel N

CVE-2024-29976 MEDIUM POC
6.5 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The improper privilege management vulnerability in the command “show_allsessions” in Zyx

CVE-2019-10632 MEDIUM POC
6.5 Apr 09

A directory traversal vulnerability in the file browser component on the Zyxel NAS 326 version 5.21 and below allows a l

CVE-2024-6342 CRITICAL
9.8 Sep 10

**UNSUPPORTED WHEN ASSIGNED** A command injection vulnerability in the export-cgi program of Zyxel NAS326 firmware versi

CVE-2023-4474 CRITICAL
9.8 Nov 30

The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0

CVE-2023-4473 CRITICAL
9.8 Nov 30

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

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