CVE-2023-28771
CRITICALCISA KEVEPSS 100th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
Zyxel Multiple Firewalls OS Command Injection Vulnerability
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.
Apply updates per vendor instructions.
Remediation due: 2023-06-21
References
Related Vulnerabilities
Other CWE-78 (OS Command Injection) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-1498 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2014-6271 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2019-16920 | Critical | 9.8 | 100% | KEV | - |
| CVE-2022-44877 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2020-8515 | Critical | 9.8 | 100% | KEV | - |
| CVE-2024-4577 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2023-28771?
Published advisories record a fix for 19 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2023-28771 being actively exploited?
Yes. CVE-2023-28771 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. US federal agencies were required to remediate it by 2023-06-21. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2023-28771?
CVE-2023-28771 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2023-28771 affect?
Published advisories record a fix for atp100 firmware (NVD), atp100w firmware (NVD), atp200 firmware (NVD), atp500 firmware (NVD), and 15 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-27.