CVE-2023-28771

Zyxel ZyWALL/USG series firmware, Zyxel VPN series firmware, Zyxel USG FLEX series firmware

Published 25 Apr 2023 · updated 17 Jun 2026 · Analyzed

9.8 Critical · CVSS 3.1, zyxel.com.tw

Exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on 31 May 2023, with a remediation deadline of 21 Jun 2023 for US federal agencies.

Required action: Apply updates per vendor instructions.

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, Third Party Advisory
www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls · Vendor Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-28771 · US Government Resource