# CVE-2023-28771: Zyxel Multiple Firewalls OS Command Injection Vulnerability

> CVE-2023-28771: Zyxel Multiple Firewalls OS Command Injection Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2023-28771
Last updated: 2025-10-21T23:05:48Z

- Published: 2023-04-25 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: 99.3%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2023-05-31, federal due date 2023-06-21, ransomware use: Unknown
- CWE: CWE-78

## Description

Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- Zyxel: ATP series 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-2023-28771)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2023-28771)
- [http://packetstormsecurity.com/files/172820/Zyxel-IKE-Packet-Decoder-Unauthenticated-Remote-Code-Execution.html](http://packetstormsecurity.com/files/172820/Zyxel-IKE-Packet-Decoder-Unauthenticated-Remote-Code-Execution.html)
- [https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls](https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls)

---

_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/)_


---
Canonical: https://rewindex.com/cve/CVE-2023-28771 · Markdown: https://rewindex.com/cve/CVE-2023-28771.md · JSON: https://rewindex.com/api/v1/cves/CVE-2023-28771 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:08:57.736Z