medium
6.5
CWE
476
Advisory Published
Updated

CVE-2023-6397: Null Pointer Dereference

First published: Tue Feb 20 2024(Updated: )

A null pointer dereference vulnerability in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1 and USG FLEX series firmware versions from 4.50 through 5.37 Patch 1 could allow a LAN-based attacker to cause denial-of-service (DoS) conditions by downloading a crafted RAR compressed file onto a LAN-side host if the firewall has the “Anti-Malware” feature enabled.

Credit: security@zyxel.com.tw

Affected SoftwareAffected VersionHow to fix
Zyxel ATP series firmware>=4.32<=5.37 Patch 1
Zyxel USG FLEX series firmware>=4.50<=5.37 Patch 1
All of
Any of
Zyxel ZyWall ATP100 Firmware>=4.32<5.37
Zyxel ZyWall ATP100 Firmware=5.37
Zyxel ZyWall ATP100 Firmware=5.37-patch1
Zyxel ATP100 Firmware
All of
Any of
Zyxel ATP100W Firmware>=4.32<5.37
Zyxel ATP100W Firmware=5.37
Zyxel ATP100W Firmware=5.37-patch1
Zyxel ATP100W Firmware
All of
Any of
Zyxel ATP200 firmware>=4.32<5.37
Zyxel ATP200 firmware=5.37
Zyxel ATP200 firmware=5.37-patch1
Zyxel Zywall ATP200
All of
Any of
Zyxel ATP500 Firmware>=4.32<5.37
Zyxel ATP500 Firmware=5.37
Zyxel ATP500 Firmware=5.37-patch1
Zyxel ATP500 Firmware
All of
Any of
Zyxel Zywall ATP700>=4.32<5.37
Zyxel Zywall ATP700=5.37
Zyxel Zywall ATP700=5.37-patch1
Zyxel ATP700 Firmware
All of
Any of
Zyxel Zywall ATP800 Firmware>=4.32<5.37
Zyxel Zywall ATP800 Firmware=5.37
Zyxel Zywall ATP800 Firmware=5.37-patch1
Zyxel Zywall ATP800 Firmware
All of
Any of
Zyxel USG Flex 100 firmware>=4.50<5.37
Zyxel USG Flex 100 firmware=5.37
Zyxel USG Flex 100 firmware=5.37-patch1
Zyxel USG Flex 100 firmware
All of
Any of
Zyxel USG FLEX 100ax firmware>=4.50<5.37
Zyxel USG FLEX 100ax firmware=5.37
Zyxel USG FLEX 100ax firmware=5.37-patch1
Zyxel USG FLEX 100ax firmware
All of
Any of
Zyxel USG FLEX 100ax firmware>=4.50<5.37
Zyxel USG FLEX 100ax firmware=5.37
Zyxel USG FLEX 100ax firmware=5.37-patch1
Zyxel USG Flex 100HP
All of
Any of
Zyxel USG FLEX 100w firmware>=4.50<5.37
Zyxel USG FLEX 100w firmware=5.37
Zyxel USG FLEX 100w firmware=5.37-patch1
Zyxel USG FLEX 100w firmware
All of
Any of
Zyxel USG FLEX firmware>=4.50<5.37
Zyxel USG FLEX firmware=5.37
Zyxel USG FLEX firmware=5.37-patch1
Zyxel USG FLEX 200 firmware
All of
Any of
Zyxel USG Flex 200HP Firmware>=4.50<5.37
Zyxel USG Flex 200HP Firmware=5.37
Zyxel USG Flex 200HP Firmware=5.37-patch1
Zyxel USG FLEX 200h firmware
All of
Any of
Zyxel USG Flex 200HP Firmware>=4.50<5.37
Zyxel USG Flex 200HP Firmware=5.37
Zyxel USG Flex 200HP Firmware=5.37-patch1
Zyxel USG Flex 200HP Firmware
All of
Any of
Zyxel USG FLEX 50(W) series firmware>=4.50<5.37
Zyxel USG FLEX 50(W) series firmware=5.37
Zyxel USG FLEX 50(W) series firmware=5.37-patch1
Zyxel USG FLEX 50w
All of
Any of
Zyxel USG FLEX firmware>=4.50<5.37
Zyxel USG FLEX firmware=5.37
Zyxel USG FLEX firmware=5.37-patch1
Zyxel USG FLEX 500 firmware
All of
Any of
Zyxel USG FLEX 500h>=4.50<5.37
Zyxel USG FLEX 500h=5.37
Zyxel USG FLEX 500h=5.37-patch1
Zyxel USG FLEX 500h firmware
All of
Any of
Zyxel USG FLEX 50w>=4.50<5.37
Zyxel USG FLEX 50w=5.37
Zyxel USG FLEX 50w=5.37-patch1
Zyxel USG FLEX 50(W) series firmware
All of
Any of
Zyxel USG FLEX firmware>=4.50<5.37
Zyxel USG FLEX firmware=5.37
Zyxel USG FLEX firmware=5.37-patch1
Zyxel USG FLEX 700 firmware
All of
Any of
Zyxel USG FLEX 700h firmware>=4.50<5.37
Zyxel USG FLEX 700h firmware=5.37
Zyxel USG FLEX 700h firmware=5.37-patch1
Zyxel USG FLEX 700h firmware

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Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2023-6397?

    CVE-2023-6397 is classified as a denial-of-service vulnerability.

  • How do I fix CVE-2023-6397?

    To fix CVE-2023-6397, update Zyxel ATP and USG FLEX series firmware to versions 5.37 Patch 2 or later.

  • Which Zyxel firmware versions are affected by CVE-2023-6397?

    CVE-2023-6397 affects Zyxel ATP series firmware versions 4.32 to 5.37 Patch 1 and USG FLEX series firmware versions 4.50 to 5.37 Patch 1.

  • Can CVE-2023-6397 be exploited remotely?

    CVE-2023-6397 requires a LAN-based attacker to exploit the vulnerability.

  • What type of attack can CVE-2023-6397 facilitate?

    CVE-2023-6397 can cause denial-of-service (DoS) conditions on affected devices.

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