Zyxel ATP/USG FLEX/USG FLEX 50/USG20-VPN up to 5.41 os command injection

Summaryinfo

A vulnerability classified as critical was found in Zyxel ATP, USG FLEX, USG FLEX 50 and USG20-VPN up to 5.41. The impacted element is an unknown function. Executing a manipulation can lead to os command injection. This vulnerability appears as CVE-2025-11730. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in Zyxel ATP, USG FLEX, USG FLEX 50 and USG20-VPN up to 5.41. It has been declared as critical. This vulnerability affects an unknown function. The manipulation with an unknown input leads to a os command injection vulnerability. The CWE definition for the vulnerability is CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

A post‑authentication command injection vulnerability in the Dynamic DNS (DDNS) configuration CLI command in Zyxel ATP series firmware versions from V5.35 through V5.41, USG FLEX series firmware versions from V5.35 through V5.41, USG FLEX 50(W) series firmware versions from V5.35 through V5.41, and USG20(W)-VPN series firmware versions from V5.35 through V5.41 could allow an authenticated attacker with administrator privileges to execute operating system (OS) commands on an affected device by supplying a specially crafted string as an argument to the CLI command.

The advisory is shared for download at zyxel.com. This vulnerability was named CVE-2025-11730 since 10/14/2025. The exploitation appears to be easy. The attack can be initiated remotely. Additional levels of successful authentication are necessary for exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 02/05/2026). The MITRE ATT&CK project declares the attack technique as T1202.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Network Encryption Software

Vendor

• Zyxel

Name

• ATP
• USG20-VPN
• USG FLEX
• USG FLEX 50

Version

• 5.0
• 5.1
• 5.2
• 5.3
• 5.4
• 5.5
• 5.6
• 5.7
• 5.8
• 5.9
• 5.10
• 5.11
• 5.12
• 5.13
• 5.14
• 5.15
• 5.16
• 5.17
• 5.18
• 5.19
• 5.20
• 5.21
• 5.22
• 5.23
• 5.24
• 5.25
• 5.26
• 5.27
• 5.28
• 5.29
• 5.30
• 5.31
• 5.32
• 5.33
• 5.34
• 5.35
• 5.36
• 5.37
• 5.38
• 5.39
• 5.40
• 5.41

License

• commercial

Website

• Vendor: https://www.zyxel.com/

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