High severity · published Oct 21, 2025
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)…
8.1
CVSS
5.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)5.5% · higher than 93% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AS
ATP series firmware · Zyxel
versions from V4.32 through V5.40 · source: vendor
UF
USG FLEX 50(W) series firmware · Zyxel
versions from V4.16 through V5.40 · source: vendor
UF
USG FLEX series firmware · Zyxel
versions from V4.50 through V5.40 · source: vendor
US
USG20(W)-VPN series firmware · Zyxel
versions from V4.16 through V5.40 · source: vendor
ZL
Zld · Zyxel
4.32 before 5.41; 4.50 before 5.41; 4.16 before 5.41 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-9133
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-9133
Vendor Advisory
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-post-authentication-command-injection-and-missing-authorization-vulnerabilities-in-zld-firewalls-10-21-2025
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