CVE Watch—

CVE-2023-28771

Zyxel Multiple Firewalls OS Command Injection Vulnerability

CVSS

—

No CVSS

EPSS

99.3%

p100

KEV

YES

May 31, 2023

Exploit Today

0-100

Published: — · Last modified: —

EPSS · 30d

99.3%EPSS · 30 days99.3%

2026-06-302026-07-16

KEV catalog record

Product

Zyxel / Multiple Firewalls

Vulnerability

Zyxel Multiple Firewalls OS Command Injection Vulnerability

Added to KEV

May 31, 2023

Remediate by

Jun 21, 2023

Known ransomware use

Summary description

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.

Required action

Apply updates per vendor instructions.

Notes

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

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