ATP series firmware: Missing Authorization
CVE-2025-9133 is a high-severity missing authorization vulnerability in ATP series firmware from Zyxel, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected ATP series firmware versions: versions from V4.32 through V5.40. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 5.81% chance of exploitation within 30 days, which is in the top 6.74% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Zld to 5.41 or a later version.
- Read the advisory on zyxel.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zyxel | ATP series firmware | versions from V4.32 through V5.40 | Not stated |
| Zyxel | USG FLEX series firmware | versions from V4.50 through V5.40 | Not stated |
| Zyxel | USG FLEX 50(W) series firmware | versions from V4.16 through V5.40 | Not stated |
| Zyxel | USG20(W)-VPN series firmware | versions from V4.16 through V5.40 | Not stated |
| Zyxel | Zld | 4.32 up to, but not including, 5.41; 4.50 up to, but not including, 5.41; 4.16 up to, but not including, 5.41 | 5.41 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (zyxel.com.tw).
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Missing Authorization
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
How developers prevent this class of flaw
- Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework and the OWASP ESAPI Access Control feature.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in ATP series firmware
- 7.2 High severity
- 7.2 High severity
- 7.2 High severity
- 9.8 Critical severity
Zyxel Multiple Firewalls Path Traversal Exploited
- 7.2 High severity
- 7.2 High severity
Recent Missing Authorization vulnerabilities
- 8.1 High severity
- 8.6 High severity
- 8.1 High severity
- 8.1 High severity
- 8.8 High severity
- 7.2 High severity
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