CVE-2023-22913Network attack vector

Authenticated service interruption via CGI command injection

Published Apr 24, 2023 · Updated Feb 12, 2025

Command injection in Zyxel USG FLEX 4.50 through 5.35 and VPN 4.30 through 5.35 firmware allows remote authenticated users to interrupt service. The account_operator.cgi CGI permits injected commands during account-configuration processing, but Zyxel has not disclosed the affected parameter or shell invocation. Exploitation requires management authentication; WAN access is disabled by default, and the documented result is configuration modification that creates a denial-of-service condition.

CVSS severity8.1
High
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Zyxel USG FLEX 4.50 through 5.35 and VPN 4.30 through 5.35 firmware allows remote authenticated users to interrupt service. The account_operator.cgi CGI permits injected commands during account-configuration processing, but Zyxel has not disclosed the affected parameter or shell invocation. Exploitation requires management authentication; WAN access is disabled by default, and the documented result is configuration modification that creates a denial-of-service condition.

The record

CVE
CVE-2023-22913
Published
Apr 24, 2023
Updated
Feb 12, 2025
Vendor
Zyxel Networks
Product
Zyxel VPN Series Firmware
Classifications
CWE-77, T1499.004, T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 12, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=4.30 through 5.35

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Zyxel Networks · Zyxel VPN Series Firmwareversion=4.30 through 5.35
Zyxel Networks · Zyxel USG FLEX Series Firmwareversion=4.50 through 5.35

Published CVSS scores

8.1Zyxel CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1499.004Application or System Exploitation
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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