Exploited
critical
9.8
CWE
119 120
Advisory Published
Updated

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

First published: Wed May 24 2023(Updated: )

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.

Credit: security@zyxel.com.tw security@zyxel.com.tw

Affected SoftwareAffected VersionHow to fix
Zyxel Multiple Firewalls
Zyxel ATP100 Firmware>=4.32<5.36
Zyxel ATP100 Firmware=5.36
Zyxel ATP100 Firmware=5.36-patch1
Zyxel ATP100 Firmware
Zyxel ATP200 firmware>=4.32<5.36
Zyxel ATP200 firmware=5.36
Zyxel ATP200 firmware=5.36-patch1
Zyxel ATP200 firmware
Zyxel ATP500 Firmware>=4.32<5.36
Zyxel ATP500 Firmware=5.36
Zyxel ATP500 Firmware=5.36-patch1
Zyxel ATP500 Firmware
Zyxel ATP100W Firmware>=4.32<5.36
Zyxel ATP100W Firmware=5.36
Zyxel ATP100W Firmware=5.36-patch1
Zyxel ATP100W Firmware
Zyxel ATP700 Firmware>=4.32<5.36
Zyxel ATP700 Firmware=5.36
Zyxel ATP700 Firmware=5.36-patch1
Zyxel ATP700 Firmware
Zyxel ATP800>=4.32<5.36
Zyxel ATP800=5.36
Zyxel ATP800=5.36-patch1
Zyxel ATP800 Firmware
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(W) series firmware=5.36
Zyxel USG FLEX 50(W) series firmware=5.36-patch1
Zyxel USG FLEX 50
Zyxel USG FLEX 200>=4.50<5.36
Zyxel USG FLEX 200=5.36
Zyxel USG FLEX 200=5.36-patch1
Zyxel USG FLEX 200 firmware
Zyxel USG FLEX 500>=4.50<5.36
Zyxel USG FLEX 500=5.36
Zyxel USG FLEX 500=5.36-patch1
Zyxel USG FLEX 500 firmware
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 firmware
Zyxel USG FLEX 100w firmware=5.36
Zyxel USG FLEX 100w firmware=5.36-patch1
Zyxel USG FLEX 100w firmware
Zyxel USG FLEX 50w>=4.25<5.36
Zyxel USG FLEX 50w=5.36
Zyxel USG FLEX 50w=5.36-patch1
Zyxel USG FLEX 50(W) series firmware
Zyxel USG 20w-VPN Firmware=5.36
Zyxel USG 20w-VPN Firmware=5.36-patch1
Zyxel USG20
Zyxel VPN100>=4.30<5.36
Zyxel VPN100=5.36
Zyxel VPN100=5.36-patch1
Zyxel VPN100 Firmware
Zyxel Zywall VPN 50 Firmware>=4.30<5.36
Zyxel Zywall VPN 50 Firmware=5.36
Zyxel Zywall VPN 50 Firmware=5.36-patch1
Zyxel VPN50 Firmware
Zyxel Zywall VPN 300 Firmware>=4.30<5.36
Zyxel Zywall VPN 300 Firmware=5.36
Zyxel Zywall VPN 300 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 Firmware
Zyxel USG20-VPN Firmware>=4.30<5.36
Zyxel USG20-VPN Firmware=5.36
Zyxel USG20-VPN Firmware=5.36-patch1
Zyxel USG20
Zyxel USG 40 firmware>=4.25<4.73
Zyxel USG 40 firmware=4.73
Zyxel USG 40 firmware=4.73-patch1
Zyxel USG40W
Zyxel USG40W Firmware>=4.25<4.73
Zyxel USG40W Firmware=4.73
Zyxel USG40W Firmware=4.73-patch1
Zyxel USG40W
Zyxel USG60W Firmware>=4.25<4.73
Zyxel USG60W Firmware=4.73
Zyxel USG60W Firmware=4.73-patch1
Zyxel USG 60w firmware
Zyxel USG60 Firmware>=4.25<4.73
Zyxel USG60 Firmware=4.73
Zyxel USG60 Firmware=4.73-patch1
Zyxel USG60W
All of
Any of
Zyxel ATP100 Firmware>=4.60<5.36
Zyxel ATP100 Firmware=5.36
Zyxel ATP100 Firmware=5.36-patch1
Zyxel ATP100 Firmware
All of
Any of
Zyxel ATP200 firmware>=4.60<5.36
Zyxel ATP200 firmware=5.36
Zyxel ATP200 firmware=5.36-patch1
Zyxel ATP200 firmware
All of
Any of
Zyxel ATP500 Firmware>=4.60<5.36
Zyxel ATP500 Firmware=5.36
Zyxel ATP500 Firmware=5.36-patch1
Zyxel ATP500 Firmware
All of
Any of
Zyxel ATP100W Firmware>=4.60<5.36
Zyxel ATP100W Firmware=5.36
Zyxel ATP100W Firmware=5.36-patch1
Zyxel ATP100W Firmware
All of
Any of
Zyxel ATP700 Firmware>=4.60<5.36
Zyxel ATP700 Firmware=5.36
Zyxel ATP700 Firmware=5.36-patch1
Zyxel ATP700 Firmware
All of
Any of
Zyxel ATP800>=4.60<5.36
Zyxel ATP800=5.36
Zyxel ATP800=5.36-patch1
Zyxel ATP800 Firmware
All of
Any of
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
Any of
Zyxel USG FLEX 50(W) series firmware>=4.60<5.36
Zyxel USG FLEX 50(W) series firmware=5.36
Zyxel USG FLEX 50(W) series firmware=5.36-patch1
Zyxel USG FLEX 50
All of
Any of
Zyxel USG FLEX 200>=4.60<5.36
Zyxel USG FLEX 200=5.36
Zyxel USG FLEX 200=5.36-patch1
Zyxel USG FLEX 200 firmware
All of
Any of
Zyxel USG FLEX 500>=4.60<5.36
Zyxel USG FLEX 500=5.36
Zyxel USG FLEX 500=5.36-patch1
Zyxel USG FLEX 500 firmware
All of
Any of
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 firmware
All of
Any of
Zyxel USG Flex 100 firmware>=4.60<5.36
Zyxel USG FLEX 100w firmware=5.36
Zyxel USG FLEX 100w firmware=5.36-patch1
Zyxel USG FLEX 100w firmware
All of
Any of
Zyxel USG FLEX 50w>=4.60<5.36
Zyxel USG FLEX 50w=5.36
Zyxel USG FLEX 50w=5.36-patch1
Zyxel USG FLEX 50(W) series firmware
All of
Any of
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 USG20
All of
Any of
Zyxel VPN100>=4.60<5.36
Zyxel VPN100=5.36
Zyxel VPN100=5.36-patch1
Zyxel VPN100 Firmware
All of
Any of
Zyxel Zywall VPN 50 Firmware>=4.60<5.36
Zyxel Zywall VPN 50 Firmware=5.36
Zyxel Zywall VPN 50 Firmware=5.36-patch1
Zyxel VPN50 Firmware
All of
Any of
Zyxel Zywall VPN 300 Firmware>=4.60<5.36
Zyxel Zywall VPN 300 Firmware=5.36
Zyxel Zywall VPN 300 Firmware=5.36-patch1
Zyxel VPN300
All of
Any of
Zyxel VPN1000 Firmware>=4.60<5.36
Zyxel VPN1000 Firmware=5.36
Zyxel VPN1000 Firmware=5.36-patch1
Zyxel VPN1000 Firmware
All of
Any of
Zyxel USG20-VPN Firmware>=4.60<5.36
Zyxel USG20-VPN Firmware=5.36
Zyxel USG20-VPN Firmware=5.36-patch1
Zyxel USG20
All of
Any of
Zyxel USG 40 firmware>=4.60<4.73
Zyxel USG 40 firmware=4.73
Zyxel USG 40 firmware=4.73-patch1
Zyxel USG40W
All of
Any of
Zyxel USG40W Firmware>=4.60<4.73
Zyxel USG40W Firmware=4.73
Zyxel USG40W Firmware=4.73-patch1
Zyxel USG40W
All of
Any of
Zyxel USG60W Firmware>=4.60<4.73
Zyxel USG60W Firmware=4.73
Zyxel USG60W Firmware=4.73-patch1
Zyxel USG 60w firmware
All of
Any of
Zyxel USG60 Firmware>=4.60<4.73
Zyxel USG60 Firmware=4.73
Zyxel USG60 Firmware=4.73-patch1
Zyxel USG60W

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Reference Links

Frequently Asked Questions

  • 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.

  • 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.

  • How severe is CVE-2023-33009?

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

  • 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.

  • 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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