CVE-2025-9133: High severity Zyxel ATP series firmware vulnerability

Published Oct 21, 2025
·
Updated

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.

Affected Software

23 affected components
Zyxel ATP series firmware>=V4.32<=V5.40
Zyxel USG FLEX series firmware>=V4.50<=V5.40
Zyxel USG FLEX 50(W) series firmware>=V4.16<=V5.40
Zyxel USG20(W)-VPN series firmware>=V4.16<=V5.40
All of the following
Zyxel ZLD>=4.32<5.41
Any of the following
Zyxel Atp100
Zyxel Atp100w
Zyxel ATP200
Zyxel ATP500
Zyxel Atp700
Zyxel ATP800
All of the following
Zyxel ZLD>=4.50<5.41
Any of the following
Zyxel Usg Flex 100
Zyxel Usg Flex 100ax
Zyxel Usg Flex 100w
Zyxel USG FLEX 200
Zyxel USG FLEX 50
Zyxel USG FLEX 500
Zyxel Usg Flex 50ax
Zyxel USG FLEX 700
All of the following
Zyxel ZLD>=4.16<5.41
Any of the following
Zyxel Usg 20w-vpn
Zyxel Usg Flex 50w

Event History

Oct 21, 2025
CVE Published
via MITRE·01:57 AM
Data Sourced
via MITRE·01:57 AM
DescriptionSeverityWeakness
Data Sourced
via NVD·03:15 AM
DescriptionSeverityWeaknessAffected Software
Feb 28, 57989
Event
via FIRST·08:38 AM
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Frequently Asked Questions

1

What is the severity of CVE-2025-9133?

CVE-2025-9133 is classified as a critical severity vulnerability due to its potential to allow unauthorized access to sensitive functions.

2

How do I fix CVE-2025-9133?

To address CVE-2025-9133, upgrade the affected Zyxel firmware to the latest version available permanently rectifying the vulnerability.

3

What versions are affected by CVE-2025-9133?

CVE-2025-9133 affects Zyxel ATP series, USG FLEX series, USG FLEX 50(W) series, and USG20(W)-VPN series firmware within specific version ranges.

4

What types of devices are impacted by CVE-2025-9133?

CVE-2025-9133 impacts specific Zyxel networking devices including firewalls in their ATP series, USG FLEX series, USG FLEX 50(W), and USG20(W)-VPN series.

5

Is there a workaround for CVE-2025-9133?

Currently, the recommended action for CVE-2025-9133 is to update the firmware, as there is no reliable workaround to mitigate the issue.

Contact

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