CVE-2023-34139: Zyxel Usg 2200-VPN Firmware

High severity, CVSS 8.8. EPSS: 0.8% chance of exploitation in the next 30 days.

A command injection vulnerability in the Free Time WiFi hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.36 Patch 2 and VPN series firmware versions 4.20 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device.

Affected products

• Zyxel Usg 2200-VPN Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 100 Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 100w Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 200 Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 500 Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 50 Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 50w Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Usg Flex 700 Firmware: from 4.50, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN100 Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN2S Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN300 Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN50 Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN 100 Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN 300 Firmware: from 4.20, before 5.37 (fixed in 5.37)
• Zyxel Zywall VPN 50 Firmware: from 4.20, before 5.37 (fixed in 5.37)

Published 2023-07-17. Last modified 2026-06-17.