Overview
Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG firewalls allow for improper error message handling which could allow an unauthenticated attacker to execute OS commands remotely by sending crafted packets to an affected device.
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls; https://nvd.nist.gov/vuln/detail/CVE-2023-28771
Key Details
| Property | Value |
|---|---|
| CVE ID | CVE-2023-28771 |
| Vendor / Product | Zyxel — Multiple Firewalls |
| NVD Published | 2023-04-25 |
| NVD Last Modified | 2025-10-27 |
| CVSS 3.1 Score | 9.8 |
| CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Severity | CRITICAL |
| CWE | CWE-78 |
| CISA KEV Added | 2023-05-31 |
| CISA KEV Deadline | 2023-06-21 |
| Known Ransomware Use | No |
CVSS 3.1 Breakdown
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Required Action
CISA BOD 22-01 Deadline: 2023-06-21.
Apply updates per vendor instructions.
Timeline
| Date | Event |
|---|---|
| 2023-05-31 | Added to CISA Known Exploited Vulnerabilities catalog |
| 2023-06-21 | CISA BOD 22-01 remediation deadline |
References
| Resource | Type |
|---|---|
| NVD — CVE-2023-28771 | Vulnerability Database |
| CISA KEV Catalog Entry | US Government |