CVE-2023-22913: Zyxel Usg Flex 100 Firmware

High severity, CVSS 8.1. EPSS: 1.3% chance of exploitation in the next 30 days.

A post-authentication command injection vulnerability in the “account_operator.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote authenticated attacker to modify device configuration data, resulting in denial-of-service (DoS) conditions on an affected device.

Affected products

• Zyxel Usg Flex 100 Firmware: from 4.50, up to and including 5.35
• Zyxel Usg Flex 100w Firmware: from 4.50, up to and including 5.35
• Zyxel Usg Flex 200 Firmware: from 4.50, up to and including 5.35
• Zyxel Usg Flex 500 Firmware: from 4.50, up to and including 5.35
• Zyxel Usg Flex 50 Firmware: from 4.50, up to and including 5.35
• Zyxel Usg Flex 50w Firmware: from 4.50, up to and including 5.35
• Zyxel Usg Flex 700 Firmware: from 4.50, up to and including 5.35
• Zyxel VPN1000 Firmware: from 4.50, up to and including 5.35
• Zyxel VPN100 Firmware: from 4.50, up to and including 5.35
• Zyxel VPN300 Firmware: from 4.50, up to and including 5.35
• Zyxel VPN50 Firmware: from 4.50, up to and including 5.35

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