CVE-2023-33010Known exploitationNetwork attack vector

Code execution via ID processing buffer overflow

Published May 24, 2023 · Updated Oct 21, 2025

A buffer overflow in Zyxel firewall firmware allows remote attackers to execute code or interrupt service through ID processing. Zyxel has not disclosed how the ID processing function copies or bounds attacker-controlled input. No authentication or user interaction is required; successful exploitation can run code on the appliance or leave it unresponsive.

CVSS severity9.8
Critical
EPSS probability28.81%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A buffer overflow in Zyxel firewall firmware allows remote attackers to execute code or interrupt service through ID processing. Zyxel has not disclosed how the ID processing function copies or bounds attacker-controlled input. No authentication or user interaction is required; successful exploitation can run code on the appliance or leave it unresponsive.

The record

CVE
CVE-2023-33010
Published
May 24, 2023
Updated
Oct 21, 2025
Vendor
Zyxel Networks
Product
Zyxel ATP Series Firmware
Classifications
CWE-120, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 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=4.32 through 5.36 Patch 1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · Zyxel ATP Series Firmwareversion=4.32 through 5.36 Patch 1
Zyxel Networks · Zyxel USG FLEX 50(W) Firmwareversion=4.25 through 5.36 Patch 1
Zyxel Networks · Zyxel USG20(W)-VPN Series Firmwareversion=4.25 through 5.36 Patch 1
Zyxel Networks · Zyxel ZyWALL/USG Series Firmwareversion=4.25 through 4.73 Patch 1
Zyxel Networks · Zyxel VPN Series Firmwareversion=4.30 through 5.36 Patch 1
Zyxel Networks · Zyxel USG FLEX Series Firmwareversion=4.50 through 5.36 Patch 1

Published CVSS scores

9.8Zyxel CorporationCVSS:3.1/AV:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1190Exploit Public-Facing Application

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.

Reported exploitation

Technologies

Your stack

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Your stack

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