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Vulnerability record · CVE-2023-27991 · published 24 April 2023

CVE-2023-27991: Zyxel atp200 firmware os command injection vulnerability

Zyxel · Atp200 Firmware

The post-authentication command injection vulnerability in the CLI command of Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.16 through 5.35, USG20(W)-VPN firmware versions 4.16 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow an authenticated attacker to execute some OS commands remotely.

8.8 CVSS 3.1 High EPSS 1.5% · top 27.6% CWE-78 · OS command injection
8.8CVSS 3.1 base score
1.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
19Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

The post-authentication command injection vulnerability in the CLI command of Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.16 through 5.35, USG20(W)-VPN firmware versions 4.16 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow an authenticated attacker to execute some OS commands remotely.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

19 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-xss-vulnerability-and-post-authe Vendor Advisory
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-xss-vulnerability-and-post-authe Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2023-33009Zyxel firewall notification function buffer overflowA buffer overflow in the notification function of multiple Zyxel firewall and VPN firmware lines (ATP, USG FLEX, USG20(W)-VPN, VPN, ZyWALL/USG) allow…KEVEPSS 28%analysed9.8CVE-2023-33010Zyxel firewall ID processing buffer overflow allows unauthenticated RCEA classic buffer overflow (CWE-120) exists in the ID processing function of multiple Zyxel firewall firmware lines, including ATP, USG FLEX, USG20(W)…KEVEPSS 29%analysed9.8CVE-2023-28771Zyxel firewall firmware OS command injection via crafted packetsZyxel ZyWALL/USG, VPN, USG FLEX and ATP series firmware mishandle error messages, allowing OS command injection. An unauthenticated remote attacker c…KEVEPSS 99%analysed9.8CVE-2022-30525Zyxel firewall CGI OS command injectionThe CGI program in multiple Zyxel firewall and VPN firmware lines fails to neutralize OS command syntax, allowing command injection. The flaw affects…KEVEPSS 100%analysed9.8CVE-2020-29583Zyxel USG and ATP firmware hard-coded admin credentialZyxel USG and ATP firmware version 4.60 ships an undocumented account (zyfwp) whose password is stored in cleartext in the firmware and cannot be cha…KEVEPSS 90%analysed9.8CVE-2020-9054ZyXEL NAS weblogin.cgi pre-auth command injectionZyXEL NAS devices running firmware 5.21 fail to sanitize the username parameter in the weblogin.cgi CGI executable, allowing OS command injection. Be…KEVEPSS 100%analysed9.8CVE-2022-0342Zyxel firewall CGI authentication bypass grants admin accessThe CGI program in multiple Zyxel firewall firmware lines (USG/ZyWALL, USG FLEX, ATP, VPN, NSG) fails to properly enforce authentication, allowing a …EPSS 95%analysed8.1CVE-2023-6764Zyxel atp100 firmware vulnerabilityA format string vulnerability in a function of the IPSec VPN feature in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX s…EPSS 0.89%

Source: NIST National Vulnerability Database (record CVE-2023-27991), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.