CVE-2023-22916: Zyxel ATP100 Firmware

High severity, CVSS 8.1. EPSS: 0.7% chance of exploitation in the next 30 days.

The configuration parser of Zyxel ATP series firmware versions 5.10 through 5.35, USG FLEX series firmware versions 5.00 through 5.35, USG FLEX 50(W) firmware versions 5.10 through 5.35, USG20(W)-VPN firmware versions 5.10 through 5.35, and VPN series firmware versions 5.00 through 5.35, which fails to properly sanitize user input. A remote unauthenticated attacker could leverage the vulnerability to modify device configuration data, resulting in DoS conditions on an affected device if the attacker could trick an authorized administrator to switch the management mode to the cloud mode.

Affected products

• Zyxel ATP100 Firmware: from 5.10, up to and including 5.35
• Zyxel ATP100W Firmware: from 5.10, up to and including 5.35
• Zyxel ATP200 Firmware: from 5.10, up to and including 5.35
• Zyxel ATP500 Firmware: from 5.10, up to and including 5.35
• Zyxel ATP700 Firmware: from 5.10, up to and including 5.35
• Zyxel ATP800 Firmware: from 5.10, up to and including 5.35
• Zyxel Usg 20w-VPN Firmware: from 5.10, up to and including 5.35
• Zyxel Usg Flex 100 Firmware: from 5.00, up to and including 5.35
• Zyxel Usg Flex 100w Firmware: from 5.00, up to and including 5.35
• Zyxel Usg Flex 200 Firmware: from 5.00, up to and including 5.35
• Zyxel Usg Flex 500 Firmware: from 5.00, up to and including 5.35
• Zyxel Usg Flex 50 Firmware: from 5.00, up to and including 5.35
• Zyxel Usg Flex 50w Firmware: from 5.10, up to and including 5.35
• Zyxel Usg Flex 700 Firmware: from 5.00, up to and including 5.35
• Zyxel VPN1000 Firmware: from 5.00, up to and including 5.35
• Zyxel VPN100 Firmware: from 5.00, up to and including 5.35
• Zyxel VPN300 Firmware: from 5.00, up to and including 5.35
• Zyxel VPN50 Firmware: from 5.00, up to and including 5.35

Published 2023-04-24. Last modified 2026-06-17.