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Nas326 FirmwareOperating system · Zyxel

CVE-2023-5372

HIGH · 7.2 CVSS v3.1 Published 2024-01-30
Fix available
A fix is available. Upgrade to 5.21 or later.
See remediation →
78/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The post-authentication command injection vulnerability in Zyxel NAS326 firmware versions through V5.21(AAZF.15)C0 and NAS542 firmware versions through V5.21(ABAG.12)C0 could allow an authenticated attacker with administrator privileges to execute some operating system (OS) commands by sending a crafted query parameter attached to the URL of an affected device’s web management interface.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Zyxel NAS326 and NAS542 devices contain a post-authentication command injection vulnerability in their web management interface. An authenticated attacker with administrator privileges can inject arbitrary OS commands by including them in crafted query parameters attached to URLs. The vulnerability affects firmware versions up to V5.21(AAZF.15)C0 for NAS326 and V5.21(ABAG.12)C0 for NAS542.

MitigationUpdate firmware to the latest patched version (V5.21(AAZF.16) or later for NAS326, V5.21(ABAG.13) or later for NAS542). Until patched, restrict administrative access to trusted IP addresses only and disable remote web management if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nas326 FirmwareOperating system
Affected:< 5.21\(aazf.16\)c0
Nas542 FirmwareOperating system
Affected:< 5.21\(abag.13\)c0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the NAS device model
    Check the device label or access the web management interface. The model number (NAS326 or NAS542) is displayed on the login page or in the System Status > Device Information section.
    Affected if The device is a Zyxel NAS326 or NAS542 model.
  2. Check the firmware version
    In the web UI, go to Administration > Firmware > Upload or System Status > Device Information to view the current firmware version. Alternatively, access the device via SSH/telnet and run the command: cat /etc/zyxel fw_info
    Affected if The firmware version is below V5.21(AAZF.16)C0 for NAS326, or below V5.21(ABAG.13)C0 for NAS542.
  3. Verify web management interface is enabled
    In the web UI, go to System Administration > HTTP/HTTPS Settings (or similar) to confirm if the web management interface is enabled. Also check if remote access is permitted.
    Affected if The web management interface is enabled and accessible.
  4. Check network exposure of the admin interface
    Review the firewall or access control settings to determine if the admin web interface is reachable from untrusted networks (such as the internet or guest networks).
    Affected if The admin interface is accessible from networks beyond the local trusted network.
  5. Confirm administrator accounts exist
    In the web UI, go to System Administration > User Account or similar to verify that administrator accounts are configured.
    Affected if At least one administrator account is configured on the device.

The environment is affected if the device is a NAS326 with firmware below V5.21(AAZF.16)C0, or a NAS542 with firmware below V5.21(ABAG.13)C0, AND the web management interface is enabled and exposed.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.21 or later
Fixed in 5.21
Interim mitigation

Update firmware to the latest patched version (V5.21(AAZF.16) or later for NAS326, V5.21(ABAG.13) or later for NAS542). Until patched, restrict administrative access to trusted IP addresses only and disable remote web management if not required.

Recommended fix High confidence

Nas326: V5.21(aazf.16)c0 or later; Nas542: V5.21(abag.13)c0 or later

  1. 1. Log in to the Zyxel NAS web management interface with administrator privileges
  2. 2. Navigate to the Administration or System Settings section
  3. 3. Locate the Firmware Upgrade or System Maintenance option
  4. 4. Download the appropriate firmware version from Zyxel's official support website: For Nas326, download version V5.21(aazf.16)c0 or later; For Nas542, download version V5.21(abag.13)c0 or later
  5. 5. Upload the firmware file to the device and initiate the upgrade process
  6. 6. Wait for the device to reboot and complete the firmware installation
  7. 7. Verify the firmware version has been successfully updated by checking the system information page
Caveat Firmware upgrades may temporarily interrupt device availability; ensure backups are performed before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nas326 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,300
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-5372 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data