# CVE-2023-33010: Zyxel Multiple Firewalls Buffer Overflow Vulnerability

> CVE-2023-33010: Zyxel Multiple Firewalls Buffer Overflow Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2023-33010
Last updated: 2025-10-21T23:05:47Z

- Published: 2023-05-24 00:00 UTC · Updated: 2025-10-21 23:05 UTC · Assigner: Zyxel
- CVSS: 9.8 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 29.0%, 98th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2023-06-05, federal due date 2023-06-26, ransomware use: Unknown
- CWE: CWE-120

## 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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- Zyxel: ATP series firmware
- Zyxel: USG20(W)-VPN firmware
- Zyxel: USG FLEX 50(W) firmware
- Zyxel: USG FLEX series firmware
- Zyxel: VPN series firmware
- Zyxel: ZyWALL/USG series firmware

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2023-33010)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2023-33010)
- [https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls](https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2023-33010 · Markdown: https://rewindex.com/cve/CVE-2023-33010.md · JSON: https://rewindex.com/api/v1/cves/CVE-2023-33010 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:08:59.899Z