Zyxel security advisory for post-authentication RCE in firewalls

CVE: CVE-2022-38547

Zyxel has released patches for firewalls affected by a post-authentication remote code execution (RCE) vulnerability. Users are advised to install them for optimal protection.

What is the vulnerability?

The post-authentication RCE vulnerability in the CLI command of some firewall versions could allow an authenticated attacker to execute some OS commands remotely. Note that WAN access is disabled by default on the firewall devices.

What versions are vulnerable—and what should you do?

After a thorough investigation, we’ve identified the vulnerable products that are within their vulnerability support period and released patches to address the vulnerability, as shown in the table below.

Affected series Affected version Patch availability
ATP ZLD V4.32~V5.32 ZLD V5.35
USG FLEX ZLD V4.50~V5.32 ZLD V5.35
VPN ZLD V4.30~V5.32 ZLD V5.35
ZyWALL/USG ZLD V4.20~V4.72 ZLD V4.73
Got a question?

Please contact your local service rep or visit Zyxel’s Community for further information or assistance.


Thanks to atdog from TRAPA Security for reporting the issue to us.

Revision history

2023-2-7: Initial release