Auth bypass in Zyxel Atp100
CVE-2025-9133
A missing authorization vulnerability in Zyxel ATP series firmware versions from V4.32 through V5.40, USG FLEX series firmware versions from V4.50 through V5.40, USG FLEX 50(W) series firmware versions from V4.16 through V5.40, and USG20(W)-VPN series firmware versions from V4.16 through V5.40 could allow a semi-authenticated attacker—who has completed only the first stage of the two-factor authentication (2FA) process—to view and download the system configuration from an affected device.
Vulnerability class: Broken Access Control
EPSS: 0.054 (92.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Zyxel Atp100
- Zyxel Atp100w
- Zyxel Atp200
- Zyxel Atp500
- Zyxel Atp700
- Zyxel Atp800
- Zyxel Atp Series Firmware — versions versions from V4.32 through V5.40
- Zyxel Usg_20w-vpn
- Zyxel Usg20(w)-vpn Series Firmware — versions versions from V4.16 through V5.40
- Zyxel Usg_flex_100
Weakness classification (CWE)
References
- security@zyxel.com.tw (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2025-9133?
- CVE-2025-9133 is a high-severity vulnerability in Zyxel Atp100, classified under Missing Authorization. CVSS score: 8.1/10. Published 2025-10-21.
- How severe is CVE-2025-9133?
- High severity. CVSS v3 base score is 8.1 out of 10.