Zyxel Multiple Firewalls
YES - ON THE CISA KEV LIST
CVE-2023-28771
Zyxel Multiple Firewalls OS Command Injection Vulnerability
overdue since 2023-06-21
Zyxel: 13 entries (0.7% of all KEV entries are from this vendor); 1 added in 2026.
BOD 26-04 note: this is the date printed in the CISA catalog. A federal agency's actual deadline is set by its SSVC tier - Act (3 days), Attend (14 days), Track (60 days), or the next scheduled upgrade - counted from the KEV listing date or the date the vulnerability is identified in its environment, whichever comes first. Use the tier helper on each CVE page for your own window.
Your BOD 26-04 window (SSVC tier helper)
Your remediation window ends:
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 (CISA)
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
References
Other KEV entries for this vendor: Zyxel
- CVE-2026-7273 - GS1900 Series Switches (2026-09-21)
- CVE-2024-40891 - DSL CPE Devices (2025-02-11)
- CVE-2024-40890 - DSL CPE Devices (2025-02-11)
- CVE-2024-11667 - Multiple Firewalls (2024-12-03)
- CVE-2017-6884 - EMG2926 Routers (2023-09-18)
- CVE-2017-18368 - P660HN-T1A Routers (2023-08-07)
- CVE-2023-27992 - Multiple Network-Attached Storage (NAS) Devices (2023-06-23)
- CVE-2023-33009 - Multiple Firewalls (2023-06-05)
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