CVE-2019-12581: Zyxel UAG2100 Firmware

Medium severity, CVSS 6.1. EPSS: 6.4% chance of exploitation in the next 30 days.

A reflective Cross-site scripting (XSS) vulnerability in the free_time_failed.cgi CGI program in selected Zyxel ZyWall, USG, and UAG devices allows remote attackers to inject arbitrary web script or HTML via the err_msg parameter.

Affected products

• Zyxel UAG2100 Firmware: up to and including 4.18\(aaiz.1\)c0
• Zyxel UAG4100 Firmware: up to and including 4.18\(aatd.1\)c0
• Zyxel UAG5100 Firmware: up to and including 4.18\(aapn.1\)c0
• Zyxel USG1100 Firmware: up to and including 4.30
• Zyxel USG110 Firmware: up to and including 4.30
• Zyxel USG1900 Firmware: up to and including 4.30
• Zyxel USG210 Firmware: up to and including 4.30
• Zyxel USG2200-VPN Firmware: up to and including 4.30
• Zyxel USG310 Firmware: up to and including 4.30

Published 2019-06-27. Last modified 2026-06-17.