dbcve.org
Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 26 Jun 2023.
Atp100 FirmwareOperating system · Zyxel

CVE-2023-33010

CRITICAL · 9.8 CVSS v3.1 Published 2023-05-24
Fix available
A fix is available. Upgrade to 5.36 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable 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
A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.

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

Buffer overflow vulnerability in the ID processing function of Zyxel ATP, USG FLEX, USG20(W)-VPN, VPN, and ZyWALL/USG series firewalls. An unauthenticated attacker can exploit this to cause denial of service and potentially achieve remote code execution on affected devices running firmware versions 4.25 through 5.36 Patch 1.

MitigationUpdate firmware to version 5.36 Patch 2 or later, and if immediate patching is not possible, restrict external access to the device's management interface.

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
Atp100 FirmwareOperating system
Affected:>= 4.32, < 5.36= 5.36
Atp200 FirmwareOperating system
Affected:>= 4.32, < 5.36= 5.36
Atp500 FirmwareOperating system
Affected:>= 4.32, < 5.36= 5.36
Atp100w FirmwareOperating system
Affected:>= 4.32, < 5.36= 5.36
Atp700 FirmwareOperating system
Affected:>= 4.32, < 5.36= 5.36
Atp800 FirmwareOperating system
Affected:>= 4.32, < 5.36= 5.36
Usg Flex 100 FirmwareOperating system
Affected:>= 4.50, < 5.36= 5.36
Usg Flex 50 FirmwareOperating system
Affected:= 5.36

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/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 GUI or CLI and locate the model name (ATP, USG FLEX, USG20, ZyWALL/USG, or VPN series) in the status or system information page
    Affected if Device is one of the ATP, USG FLEX, USG20(W)-VPN, VPN, or ZyWALL/USG series
  2. Check the installed firmware version
    In the web GUI, go to Maintenance > Firmware > Firmware Package or use the CLI command 'show system-info' to retrieve the current firmware version
    Affected if Firmware version matches the affected ranges for the specific model (e.g., ATP100: >=4.32 and <5.36, or exactly 5.36; USG Flex 100: >=4.50 and <5.36, or exactly 5.36)
  3. Verify the ID processing function is accessible
    Check if the ID processing feature or service is enabled in the device configuration under Security Services or ID processing settings; confirm the feature is active and reachable via network
    Affected if The ID processing function is enabled and exposed to network traffic, as the buffer overflow occurs in this specific function

The environment is affected if the Zyxel device runs any of the affected models with firmware version within the vulnerable ranges (4.32-5.36 for ATP, 4.50-5.36 for USG Flex, or exactly 5.36) and the ID processing feature is 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 5.36 or later
Fixed in 5.36
Interim mitigation

Update firmware to version 5.36 Patch 2 or later, and if immediate patching is not possible, restrict external access to the device's management interface.

Recommended fix High confidence

Firmware version 5.36 Patch 2

  1. Access the Zyxel device's web administration interface or CLI
  2. Navigate to the firmware upgrade section (typically in Maintenance > Firmware or System > File Manager)
  3. Verify the current firmware version is one of the affected versions (4.32-5.36 or 5.36 Patch 1)
  4. Download the fixed firmware version 5.36 Patch 2 (or later stable release) from the official Zyxel support portal at www.zyxel.com/support/download/
  5. Upload the firmware file to the device and initiate the upgrade process
  6. Allow the device to reboot and complete the upgrade
  7. After reboot, verify the new firmware version is 5.36 Patch 2 or higher
Caveat Review Zyxel release notes for any configuration or feature changes between your current version and 5.36 Patch 2 before upgrading

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

Fix this in Atp100 Firmware Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-33010 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2023-33010 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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