The configuration parser fails to sanitize user-controlled input in the Zyxel ATP series firmware versions 5.10 through 5.36, USG FLEX seri…

published 2023-07-17 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-32402

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits: 0; none known

The configuration parser fails to sanitize user-controlled input in the Zyxel ATP series firmware versions 5.10 through 5.36, USG FLEX series firmware versions 5.00 through 5.36, USG FLEX 50(W) series firmware versions 5.10 through 5.36,

USG20(W)-VPN series firmware versions 5.10 through 5.36, and VPN series firmware versions 5.00 through 5.36. An unauthenticated, LAN-based attacker could leverage the vulnerability to inject some operating system (OS) commands into the device configuration data on an affected device when the cloud management mode is enabled.

Patch / fix

fixed in 20

zyxel usg_2200-vpn_firmware 5.37
zyxel usg_flex_100_firmware 5.37
zyxel usg_flex_100w_firmware 5.37
zyxel usg_flex_200_firmware 5.37
zyxel usg_flex_50_firmware 5.37
zyxel usg_flex_500_firmware 5.37
zyxel usg_flex_50w_firmware 5.37
zyxel usg_flex_700_firmware 5.37
zyxel zywall_vpn100_firmware 5.37
zyxel zywall_vpn2s_firmware 5.37
zyxel zywall_vpn300_firmware 5.37
zyxel zywall_vpn50_firmware 5.37
zyxel zywall_vpn_100_firmware 5.37
zyxel zywall_vpn_300_firmware 5.37
zyxel zywall_vpn_50_firmware 5.37
zyxel usg_20w-vpn_firmware 5.37
zyxel zywall_atp100_firmware 5.37
zyxel zywall_atp100w_firmware 5.37
zyxel zywall_atp200_firmware 5.37
zyxel zywall_atp500_firmware 5.37

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 2 y ago (2024-11-07)

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Zyxel ATP series firmware
Zyxel USG FLEX series firmware
Zyxel USG FLEX 50(W) series firmware
Zyxel USG20(W)-VPN series firmware
Zyxel VPN series firmware
zyxel atp_series_firmware
zyxel usg_flex_series_firmware
zyxel usg_flex_50\/w\/_series_firmware

Classification

Weakness

CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

zyxel.com /global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-w
vendor-advisory

Sources

CVE List CVE-2023-28767
NVD CVE-2023-28767

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary