dbcve.org
Usg 2200 Vpn FirmwareOperating system · Zyxel

CVE-2023-28767

HIGH · 8.8 CVSS v3.1 Published 2023-07-17
Fix available
A fix is available. Upgrade to 5.37 or later.
See remediation →
93/100
Remediation priority · Urgent
No privileges 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 configuration parser fails to sanitize user-controlled input in the Zyxel ATP series firmware versions 5.10 through 5.36, USG FLEX series firmware versions 5.00 through 5.36,  USG FLEX 50(W) series firmware versions 5.10 through 5.36, USG20(W)-VPN series firmware versions 5.10 through 5.36, and VPN series firmware versions 5.00 through 5.36. An unauthenticated, LAN-based attacker could leverage the vulnerability to inject some operating system (OS) commands into the device configuration data on an affected device when the cloud management mode is enabled.

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

A command injection vulnerability exists in the configuration parser of multiple Zyxel firewall series (ATP, USG FLEX, USG20W-VPN, VPN). The parser fails to sanitize user-controlled input, allowing an unauthenticated LAN-based attacker to inject OS commands into device configuration when cloud management mode is enabled.

MitigationDisable cloud management mode if not required and update firmware to a patched version beyond 5.36. Restrict LAN access to trusted users only as an interim compensating control.

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
Usg 2200 Vpn FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 100 FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 100w FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 200 FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 50 FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 500 FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 50w FirmwareOperating system
Affected:>= 5.00, < 5.37
Usg Flex 700 FirmwareOperating system
Affected:>= 5.00, < 5.37

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/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 Zyxel device model
    Access the device web interface under Status or Dashboard, or run CLI command 'show system-info' to confirm the exact model name (e.g., USG Flex 200, ATP series)
    Affected if Model is not one of the listed affected products (USG 2200 VPN, USG Flex 100/100w/200/50/50w/500/700)
  2. Check the installed firmware version
    In the web interface go to Maintenance > Firmware or use CLI command 'show version' to retrieve the firmware version number
    Affected if Firmware version is 5.00 through 5.36 (inclusive) - versions below 5.00 are not affected, 5.37 and above are patched
  3. Verify cloud management mode status
    In the web interface navigate to CONFIGURATION > Cloud Management or use CLI command 'show cloud-management status' to determine if cloud management is enabled
    Affected if Cloud management mode is turned ON - this is the required condition for the command injection to be exploitable

A device is affected only if it is one of the listed models, runs firmware version 5.00 through 5.36, AND has cloud management mode enabled.

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 5.37 or later
Fixed in 5.37
Interim mitigation

Disable cloud management mode if not required and update firmware to a patched version beyond 5.36. Restrict LAN access to trusted users only as an interim compensating control.

Recommended fix High confidence

Firmware version 5.37 or later (e.g., 5.37, 5.38, or latest stable release)

  1. 1. Identify the exact Zyxel device model (USG 2200 VPN, USG Flex 100, USG Flex 100w, USG Flex 200, USG Flex 50, USG Flex 500, USG Flex 50w, or USG Flex 700)
  2. 2. Access the device administration interface and check the current firmware version under Status or System Info
  3. 3. Navigate to the official Zyxel support website (www.zyxel.com) and locate the firmware download section for your specific device model
  4. 4. Download firmware version 5.37 or later (the first fixed release) for your device
  5. 5. In the device admin panel, go to Maintenance > Firmware Upgrade or similar section
  6. 6. Upload the downloaded firmware file and initiate the upgrade process
  7. 7. Wait for the upgrade to complete and the device to reboot
  8. 8. Verify the new firmware version is installed and the device is operational
Caveat Review Zyxel release notes for version 5.37+ to check for any configuration or feature changes that may affect your deployment; backup device configuration before upgrading

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

Fix this in Usg 2200 Vpn Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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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-2023-28767 in production — separate from our analysis above.

No notes yet

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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