Zyxel Multiple Firewalls OS Command Injection Vulnerability

CRITICAL 9.8EXPLOITED (CISA KEV)CVE-2023-28771 · Published 25/04/2023 · updated 17/06/2026

Zyxel Multiple Firewalls OS Command Injection Vulnerability. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 31/05/2023. Patch affected systems as an emergency.

Package	Affected versions	Patched versions
Multiple Firewalls Zyxel	Versions not published yet (product named by CISA KEV)

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.

References

packetstormsecurity.com/files/172820/Zyxel-IKE-Packet-Decoder-Unauthenticated-Remote-Code-Execution.html · Exploit
zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls · Vendor Advisory
cisa.gov/known-exploited-vulnerabilities-catalog · US Government Resource
CISA KEV · CVE-2023-28771

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