CVE-2019-12583: Zyxel UAG2100 Firmware

Critical severity, CVSS 9.1. EPSS: 43.9% chance of exploitation in the next 30 days.

Missing Access Control in the "Free Time" component of several Zyxel UAG, USG, and ZyWall devices allows a remote attacker to generate guest accounts by directly accessing the account generator. This can lead to unauthorised network access or Denial of Service.

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 4.33\(aapk.0\)c0
• Zyxel USG110 Firmware: up to and including 4.33\(aaph.0\)c0
• Zyxel USG1900 Firmware: up to and including 4.33\(aapl.0\)c0
• Zyxel USG210 Firmware: up to and including 4.33\(aapi.0\)c0
• Zyxel USG2200-VPN Firmware: up to and including 4.33\(abae.0\)c0
• Zyxel USG310 Firmware: up to and including 4.33\(aapj.0\)c0
• Zyxel Zywall 1100 Firmware: up to and including 4.33\(aaac.0\)c0
• Zyxel Zywall 110 Firmware: up to and including 4.33\(aaaa.0\)c0
• Zyxel Zywall 310 Firmware: up to and including 4.33\(aaab.0\)c0
• Zyxel Zywall VPN100 Firmware: up to and including 10.02\(abfv.0\)c0
• Zyxel Zywall VPN300 Firmware: up to and including 10.02\(abfc.0\)c0

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