---
title: "CVE-2023-33010: Buffer Copy without Checking Size of Input | CubePath"
description: "A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware…"
language: en
source: https://cubepath.com/security/cve/CVE-2023-33010
---

# CVE-2023-33010: Buffer Copy without Checking Size of Input | CubePath

## Description

A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.

Official description from the CVE record, published by Zyxel. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2023-33010)

## Key data

### CVSS 3.1 Critical 9.8

Score published by Zyxel in the CVE record.

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

| Metric                 | Value     | What it means                                                                       |
| ---------------------- | --------- | ----------------------------------------------------------------------------------- |
| Attack vector          | Network   | The vulnerable component can be reached over a network, possibly from the Internet. |
| Attack complexity      | Low       | No special conditions are needed. The attack can be repeated at will.               |
| Privileges required    | None      | No account or privileges are needed.                                                |
| User interaction       | None      | No action from any user is needed.                                                  |
| Scope                  | Unchanged | The impact stays within the vulnerable component.                                   |
| Confidentiality impact | High      | Serious or total effect on the secrecy of data.                                     |
| Integrity impact       | High      | Serious or total effect on the trustworthiness of data.                             |
| Availability impact    | High      | Serious or total effect on availability.                                            |

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) .

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score

0.29024 (29.0% probability)

Percentile

98.2%

Scores of

Nov 10, 2026

Model

v2026.06.15

### CISA Known Exploited Vulnerabilities

This CVE is listed in the CISA KEV catalog.

Name in the catalog

Zyxel Multiple Firewalls Buffer Overflow Vulnerability

Added to the catalog

Jun 5, 2023

Federal due date

Jun 26, 2023

### CISA assessment as of Jan 16, 2025

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.

Exploitation

Recorded by CISA as active

Automatable

yes

Technical impact

total

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-120](https://cwe.mitre.org/data/definitions/120.html) Buffer Copy without Checking Size of Input

## Affected products

Products listed in the CVE record, as the CNA published them.

- Zyxel ATP series firmware

  - affected: 4.32 through 5.36 Patch 1
- Zyxel USG FLEX series firmware

  - affected: 4.50 through 5.36 Patch 1
- Zyxel USG FLEX 50(W) firmware

  - affected: 4.25 through 5.36 Patch 1
- Zyxel USG20(W)-VPN firmware

  - affected: 4.25 through 5.36 Patch 1
- Zyxel VPN series firmware

  - affected: 4.30 through 5.36 Patch 1
- Zyxel ZyWALL/USG series firmware

  - affected: 4.25 through 4.73 Patch 1

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [zyxel.com/global/en/support/security-advisories/zyxel-secur…](https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls)

## Timeline

1. ID reserved May 17, 2023
2. Record published May 24, 2023
3. Added to CISA KEV Jun 5, 2023
4. Record last updated Oct 21, 2025

## Look up another CVE

## About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

[Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection)

Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:26 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)