CVE-2023-35136 - An improper input validation vulnerability in the “Quagga” package of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an authenticated local attacker to access configuration files on an affected device

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MEDIUM

An improper input validation vulnerability in the “Quagga” package of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an authenticated local attacker to access configuration files on an affected device

Published Nov 28, 2023

5.5

MEDIUM

CVSS 3.1

EPSS 0.24%

Description

An improper input validation vulnerability in the “Quagga” package of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an authenticated local attacker to access configuration files on an affected device.

Affected products

Vendor Zyxel Product ATP series firmware Default
unaffected
Affected
- versions 4.32 through 5.37
Vendor Zyxel Product USG FLEX 50(W) series firmware Default
unaffected
Affected
- versions 4.16 through 5.37
Vendor Zyxel Product USG FLEX series firmware Default
unaffected
Affected
- versions 4.50 through 5.37
Vendor Zyxel Product USG20(W)-VPN series firmware Default
unaffected
Affected
- versions 4.16 through 5.37
Vendor Zyxel Product VPN series firmware Default
unaffected
Affected
- versions 4.30 through 5.37

Default status is the baseline for the product. Each version can override it (patched versions can be marked unaffected).

Vendor	Product	Default status	Versions
Zyxel	ATP series firmware	unaffected	Affected versions 4.32 through 5.37
Zyxel	USG FLEX 50(W) series firmware	unaffected	Affected versions 4.16 through 5.37
Zyxel	USG FLEX series firmware	unaffected	Affected versions 4.50 through 5.37
Zyxel	USG20(W)-VPN series firmware	unaffected	Affected versions 4.16 through 5.37
Zyxel	VPN series firmware	unaffected	Affected versions 4.30 through 5.37

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-20

Improper Input Validation

References (2)

https://euvd.enisa.europa.eu/vulnerability/EUVD-2023-39166
Advisory
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps
vendor-advisoryVendor Advisory

Link	Providers	Tags
https://euvd.enisa.europa.eu/vulnerability/EUVD-2023-39166		Advisory
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps		vendor-advisoryVendor Advisory

Change history (0)

No recorded changes yet.

Sources

CVE.org / MITRE

Status PUBLISHED

Assigner Zyxel

Published Nov 28, 2023

Updated Jun 5, 2025

Reserved Jun 14, 2023

Link CVE-2023-35136

CISA Vulnrichment

Updated Jun 5, 2025

NVD

Status Modified

Modified Jun 17, 2026

Link CVE-2023-35136

Red Hat

No data

ENISA EUVD

Assigner Zyxel

Published Nov 28, 2023

Updated Jun 5, 2025

Link EUVD-2023-39166

GitHub

No data