A command injection vulnerability in the configuration parser of the Zyxel ATP series firmware versions 5.10 through 5.36 Patch 2, USG FLEX…

published 2023-07-17 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-37201

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 9.9%; EPSS 9.9% chance of exploitation in 30 days, percentile 95%
public exploits: 1; Metasploit

A command injection vulnerability in the configuration parser of the Zyxel ATP series firmware versions 5.10 through 5.36 Patch 2, USG FLEX series firmware versions 5.00 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 5.10 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 5.10 through 5.36 Patch 2, and VPN series firmware versions 5.00 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands by using a crafted GRE configuration when the cloud management mode is enabled.

Patch / fix

fixed in 20

zyxel usg_20w-vpn_firmware 5.37
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_atp100_firmware 5.37
zyxel zywall_atp100w_firmware 5.37
zyxel zywall_atp200_firmware 5.37
zyxel zywall_atp500_firmware 5.37
zyxel zywall_atp700_firmware 5.37
zyxel zywall_atp800_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

Timeline

2023-07-17 Published
2024-01-24 First public exploit (Metasploit exploit/linux/http/zyxel_parse_config_rce)

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 20 mo ago (2025-03-05)

Exploit prediction

9.88% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

Metasploit exploit/linux/http/zyxel_parse_config_rce Zyxel parse_config.py Command Injection metasploit exploit, normal rank, 2024-01-24

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

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-2023-33012
NVD CVE-2023-33012

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