CVE-2023-33009: Zyxel Multiple Firewalls Buffer Overflow Vulnerability

Published May 24, 2023
·
Updated

A buffer overflow vulnerability in the notification 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.

Other sources

A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX series firmware versions 4.60 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.60 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.60 through 5.36 Patch 1, VPN series firmware versions 4.60 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.60 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.

Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow vulnerability in the notification function that could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and remote code execution on an affected device.

— CISA

Affected Software

182 affected components
Zyxel Multiple Firewalls
Zyxel Atp100 Firmware>=4.32<5.36
Zyxel Atp100 Firmware=5.36
Zyxel Atp100 Firmware=5.36-patch1
Zyxel Atp100
Zyxel Atp200 Firmware>=4.32<5.36
Zyxel Atp200 Firmware=5.36
Zyxel Atp200 Firmware=5.36-patch1
Zyxel ATP200
Zyxel Atp500 Firmware>=4.32<5.36
Zyxel Atp500 Firmware=5.36
Zyxel Atp500 Firmware=5.36-patch1
Zyxel ATP500
Zyxel Atp100w Firmware>=4.32<5.36
Zyxel Atp100w Firmware=5.36
Zyxel Atp100w Firmware=5.36-patch1
Zyxel Atp100w
Zyxel Atp700 Firmware>=4.32<5.36
Zyxel Atp700 Firmware=5.36
Zyxel Atp700 Firmware=5.36-patch1
Zyxel Atp700
Zyxel Atp800 Firmware>=4.32<5.36
Zyxel Atp800 Firmware=5.36
Zyxel Atp800 Firmware=5.36-patch1
Zyxel ATP800
Zyxel Usg Flex 100 Firmware>=4.50<5.36
Zyxel Usg Flex 100 Firmware=5.36
Zyxel Usg Flex 100 Firmware=5.36-patch1
Zyxel Usg Flex 100
Zyxel Usg Flex 50 Firmware=5.36
Zyxel Usg Flex 50 Firmware=5.36-patch1
Zyxel USG FLEX 50
Zyxel USG FLEX 200 firmware>=4.50<5.36
Zyxel USG FLEX 200 firmware=5.36
Zyxel USG FLEX 200 firmware=5.36-patch1
Zyxel USG FLEX 200
Zyxel USG FLEX 500 firmware>=4.50<5.36
Zyxel USG FLEX 500 firmware=5.36
Zyxel USG FLEX 500 firmware=5.36-patch1
Zyxel USG FLEX 500
Zyxel USG FLEX 700 firmware>=4.50<5.36
Zyxel USG FLEX 700 firmware=5.36
Zyxel USG FLEX 700 firmware=5.36-patch1
Zyxel USG FLEX 700
Zyxel Usg Flex 100w Firmware=5.36
Zyxel Usg Flex 100w Firmware=5.36-patch1
Zyxel Usg Flex 100w
Zyxel Usg Flex 50w Firmware>=4.25<5.36
Zyxel Usg Flex 50w Firmware=5.36
Zyxel Usg Flex 50w Firmware=5.36-patch1
Zyxel Usg Flex 50w
Zyxel Usg 20w-vpn Firmware=5.36
Zyxel Usg 20w-vpn Firmware=5.36-patch1
Zyxel Usg 20w-vpn
Zyxel Vpn100 Firmware>=4.30<5.36
Zyxel Vpn100 Firmware=5.36
Zyxel Vpn100 Firmware=5.36-patch1
Zyxel Vpn100
Zyxel Vpn50 Firmware>=4.30<5.36
Zyxel Vpn50 Firmware=5.36
Zyxel Vpn50 Firmware=5.36-patch1
Zyxel Vpn50
Zyxel Vpn300 Firmware>=4.30<5.36
Zyxel Vpn300 Firmware=5.36
Zyxel Vpn300 Firmware=5.36-patch1
Zyxel Vpn300
Zyxel Vpn1000 Firmware>=4.30<5.36
Zyxel Vpn1000 Firmware=5.36
Zyxel Vpn1000 Firmware=5.36-patch1
Zyxel Vpn1000
Zyxel Usg20-vpn Firmware>=4.30<5.36
Zyxel Usg20-vpn Firmware=5.36
Zyxel Usg20-vpn Firmware=5.36-patch1
Zyxel USG20-VPN
Zyxel Usg 40 Firmware>=4.25<4.73
Zyxel Usg 40 Firmware=4.73
Zyxel Usg 40 Firmware=4.73-patch1
Zyxel Usg 40
Zyxel Usg 40w Firmware>=4.25<4.73
Zyxel Usg 40w Firmware=4.73
Zyxel Usg 40w Firmware=4.73-patch1
Zyxel Usg 40w
Zyxel Usg 60w Firmware>=4.25<4.73
Zyxel Usg 60w Firmware=4.73
Zyxel Usg 60w Firmware=4.73-patch1
Zyxel Usg 60w
Zyxel Usg 60 Firmware>=4.25<4.73
Zyxel Usg 60 Firmware=4.73
Zyxel Usg 60 Firmware=4.73-patch1
Zyxel Usg 60
All of the following
Any of the following
Zyxel Atp100 Firmware>=4.60<5.36
Zyxel Atp100 Firmware=5.36
Zyxel Atp100 Firmware=5.36-patch1
Zyxel Atp100
All of the following
Any of the following
Zyxel Atp200 Firmware>=4.60<5.36
Zyxel Atp200 Firmware=5.36
Zyxel Atp200 Firmware=5.36-patch1
Zyxel ATP200
All of the following
Any of the following
Zyxel Atp500 Firmware>=4.60<5.36
Zyxel Atp500 Firmware=5.36
Zyxel Atp500 Firmware=5.36-patch1
Zyxel ATP500
All of the following
Any of the following
Zyxel Atp100w Firmware>=4.60<5.36
Zyxel Atp100w Firmware=5.36
Zyxel Atp100w Firmware=5.36-patch1
Zyxel Atp100w
All of the following
Any of the following
Zyxel Atp700 Firmware>=4.60<5.36
Zyxel Atp700 Firmware=5.36
Zyxel Atp700 Firmware=5.36-patch1
Zyxel Atp700
All of the following
Any of the following
Zyxel Atp800 Firmware>=4.60<5.36
Zyxel Atp800 Firmware=5.36
Zyxel Atp800 Firmware=5.36-patch1
Zyxel ATP800
All of the following
Any of the following
Zyxel Usg Flex 100 Firmware>=4.60<5.36
Zyxel Usg Flex 100 Firmware=5.36
Zyxel Usg Flex 100 Firmware=5.36-patch1
Zyxel Usg Flex 100
All of the following
Any of the following
Zyxel Usg Flex 50 Firmware>=4.60<5.36
Zyxel Usg Flex 50 Firmware=5.36
Zyxel Usg Flex 50 Firmware=5.36-patch1
Zyxel USG FLEX 50
All of the following
Any of the following
Zyxel USG FLEX 200 firmware>=4.60<5.36
Zyxel USG FLEX 200 firmware=5.36
Zyxel USG FLEX 200 firmware=5.36-patch1
Zyxel USG FLEX 200
All of the following
Any of the following
Zyxel USG FLEX 500 firmware>=4.60<5.36
Zyxel USG FLEX 500 firmware=5.36
Zyxel USG FLEX 500 firmware=5.36-patch1
Zyxel USG FLEX 500
All of the following
Any of the following
Zyxel USG FLEX 700 firmware>=4.60<5.36
Zyxel USG FLEX 700 firmware=5.36
Zyxel USG FLEX 700 firmware=5.36-patch1
Zyxel USG FLEX 700
All of the following
Any of the following
Zyxel Usg Flex 100w Firmware>=4.60<5.36
Zyxel Usg Flex 100w Firmware=5.36
Zyxel Usg Flex 100w Firmware=5.36-patch1
Zyxel Usg Flex 100w
All of the following
Any of the following
Zyxel Usg Flex 50w Firmware>=4.60<5.36
Zyxel Usg Flex 50w Firmware=5.36
Zyxel Usg Flex 50w Firmware=5.36-patch1
Zyxel Usg Flex 50w
All of the following
Any of the following
Zyxel Usg 20w-vpn Firmware>=4.60<5.36
Zyxel Usg 20w-vpn Firmware=5.36
Zyxel Usg 20w-vpn Firmware=5.36-patch1
Zyxel Usg 20w-vpn
All of the following
Any of the following
Zyxel Vpn100 Firmware>=4.60<5.36
Zyxel Vpn100 Firmware=5.36
Zyxel Vpn100 Firmware=5.36-patch1
Zyxel Vpn100
All of the following
Any of the following
Zyxel Vpn50 Firmware>=4.60<5.36
Zyxel Vpn50 Firmware=5.36
Zyxel Vpn50 Firmware=5.36-patch1
Zyxel Vpn50
All of the following
Any of the following
Zyxel Vpn300 Firmware>=4.60<5.36
Zyxel Vpn300 Firmware=5.36
Zyxel Vpn300 Firmware=5.36-patch1
Zyxel Vpn300
All of the following
Any of the following
Zyxel Vpn1000 Firmware>=4.60<5.36
Zyxel Vpn1000 Firmware=5.36
Zyxel Vpn1000 Firmware=5.36-patch1
Zyxel Vpn1000
All of the following
Any of the following
Zyxel Usg20-vpn Firmware>=4.60<5.36
Zyxel Usg20-vpn Firmware=5.36
Zyxel Usg20-vpn Firmware=5.36-patch1
Zyxel USG20-VPN
All of the following
Any of the following
Zyxel Usg 40 Firmware>=4.60<4.73
Zyxel Usg 40 Firmware=4.73
Zyxel Usg 40 Firmware=4.73-patch1
Zyxel Usg 40
All of the following
Any of the following
Zyxel Usg 40w Firmware>=4.60<4.73
Zyxel Usg 40w Firmware=4.73
Zyxel Usg 40w Firmware=4.73-patch1
Zyxel Usg 40w
All of the following
Any of the following
Zyxel Usg 60w Firmware>=4.60<4.73
Zyxel Usg 60w Firmware=4.73
Zyxel Usg 60w Firmware=4.73-patch1
Zyxel Usg 60w
All of the following
Any of the following
Zyxel Usg 60 Firmware>=4.60<4.73
Zyxel Usg 60 Firmware=4.73
Zyxel Usg 60 Firmware=4.73-patch1
Zyxel Usg 60

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade Zyxel ATP series firmware to a version that resolves this vulnerability.

    Fixed in 4.32 through 5.36Patch Patch 1
  2. Upgrade

    Upgrade USG FLEX series firmware to a version that resolves this vulnerability.

    Fixed in 4.50 through 5.36Patch Patch 1
  3. Upgrade

    Upgrade USG FLEX 50(W) firmware to a version that resolves this vulnerability.

    Fixed in 4.25 through 5.36Patch Patch 1
  4. Upgrade

    Upgrade USG20(W)-VPN firmware to a version that resolves this vulnerability.

    Fixed in 4.25 through 5.36Patch Patch 1
  5. Upgrade

    Upgrade VPN series firmware to a version that resolves this vulnerability.

    Fixed in 4.30 through 5.36Patch Patch 1
  6. Upgrade

    Upgrade ZyWALL/USG series firmware to a version that resolves this vulnerability.

    Fixed in 4.25 through 4.73Patch Patch 1
  7. Upgrade

    Upgrade Zyxel ATP series firmware to a version that resolves this vulnerability.

    Fixed in 4.60 through 5.36Patch Patch 1
  8. Upgrade

    Upgrade USG FLEX series firmware to a version that resolves this vulnerability.

    Fixed in 4.60 through 5.36Patch Patch 1
  9. Upgrade

    Upgrade USG FLEX 50(W) firmware to a version that resolves this vulnerability.

    Fixed in 4.60 through 5.36Patch Patch 1
  10. Upgrade

    Upgrade USG20(W)-VPN firmware to a version that resolves this vulnerability.

    Fixed in 4.60 through 5.36Patch Patch 1
  11. Upgrade

    Upgrade VPN series firmware to a version that resolves this vulnerability.

    Fixed in 4.60 through 5.36Patch Patch 1
  12. Upgrade

    Upgrade ZyWALL/USG series firmware to a version that resolves this vulnerability.

    Fixed in 4.60 through 4.73Patch Patch 1

Event History

May 24, 2023
CVE Published
via MITRE·12:00 AM
Data Sourced
via MITRE·12:00 AM
DescriptionSeverityWeakness
Data Sourced
01:15 PM
Description
Data Sourced
via NVD·01:15 PM
DescriptionSeverityWeaknessAffected Software
Jun 5, 2023
Known Exploited
via CISA·12:00 AM
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Frequently Asked Questions

1

What is CVE-2023-33009?

CVE-2023-33009 is a buffer overflow vulnerability in the notification function in Zyxel ATP series, USG FLEX series, USG FLEX 50(W), and USG20(W)-VPN firmware versions 4.32 through 5.36 Patch 1.

2

How does CVE-2023-33009 affect Zyxel Multiple Firewalls?

CVE-2023-33009 affects Zyxel ATP series, USG FLEX series, USG FLEX 50(W), and USG20(W)-VPN firmware versions 4.32 through 5.36 Patch 1, leading to a buffer overflow vulnerability in the notification function.

3

How severe is CVE-2023-33009?

CVE-2023-33009 is a buffer overflow vulnerability with a severity rating of high.

4

Is there a patch available for CVE-2023-33009?

Yes, Zyxel has released firmware versions 5.36 Patch 2 and later to address the CVE-2023-33009 vulnerability.

5

What should I do to fix CVE-2023-33009?

To fix CVE-2023-33009, update your Zyxel firewall's firmware to version 5.36 Patch 2 or later.

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