CVE-2023-28771 Zyxel Multiple Firewalls OS Command Injection

Exploited in the wild Critical 9.8 Published 25 Apr 2023 Updated 21 Oct 2025

Unauthenticated attackers can execute OS commands on Zyxel firewalls via crafted packets due to improper error handling.

Exploited in the wild: Since 31 May 2023
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2023-28771?

CVE-2023-28771 is a critical command injection vulnerability in Zyxel ATP series firmware, published on 25 Apr 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-78

Which versions are affected by CVE-2023-28771?

It affects 19 products.

Products include Zyxel Atp100 Firmware, Zyxel Atp100w Firmware, Zyxel Atp200 Firmware, Zyxel Atp500 Firmware, Zyxel Atp700 Firmware, Zyxel Atp800 Firmware and 13 more.

How do I fix CVE-2023-28771?

No fix has been published for CVE-2023-28771 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 21 Jun 2023.

Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.

Is CVE-2023-28771 being exploited?

Yes. Attackers have exploited CVE-2023-28771 in the wild since at least 31 May 2023.

Public exploit code: 1 Metasploit module and 2 proofs of concept on GitHub.

Sources

Also known as GHSA-3xvp-8qg2-x43w.