CVE-2023-33012

OS command execution via crafted GRE configuration

Published Jul 17, 2023 · Updated Mar 5, 2025

OS command injection in Zyxel ATP, USG FLEX, USG20(W)-VPN, and VPN firmware through 5.36 Patch 2 allows remote attackers to execute OS commands. The configuration parser passes attacker-crafted GRE configuration data into an operating-system command context, enabling command injection. Reachability requires LAN access and cloud management mode to be enabled; successful exploitation executes some OS commands on the firewall appliance.

CVSS severity8.8
High
EPSS probability9.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Zyxel ATP, USG FLEX, USG20(W)-VPN, and VPN firmware through 5.36 Patch 2 allows remote attackers to execute OS commands. The configuration parser passes attacker-crafted GRE configuration data into an operating-system command context, enabling command injection. Reachability requires LAN access and cloud management mode to be enabled; successful exploitation executes some OS commands on the firewall appliance.

The record

CVE
CVE-2023-33012
Published
Jul 17, 2023
Updated
Mar 5, 2025
Vendor
Zyxel Networks
Product
Zyxel USG FLEX 50(W) Series Firmware
Classifications
CWE-78, T1059
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.10 through 5.36 Patch 2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Zyxel Networks · Zyxel USG FLEX 50(W) Series Firmwareversion=5.10 through 5.36 Patch 2
Zyxel Networks · Zyxel ATP Series Firmwareversion=5.10 through 5.36 Patch 2
Zyxel Networks · Zyxel USG20(W)-VPN Series Firmwareversion=5.10 through 5.36 Patch 2
Zyxel Networks · Zyxel VPN Series Firmwareversion=5.00 through 5.36 Patch 2
Zyxel Networks · Zyxel USG FLEX Series Firmwareversion=5.00 through 5.36 Patch 2

Published CVSS scores

8.8Zyxel CorporationCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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