Zyxel security advisory for XSS vulnerability in firewalls

Zyxel_May Posts: 123  Ally Member
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edited December 2022 in Security Advisories

CVE: CVE-2022-40603


Zyxel has released patches for some firewalls affected by a reflected cross-site scripting (XSS) vulnerability. Users are advised to install them for optimal protection.

What is the vulnerability?

A reflected XSS vulnerability in the CGI program of some firewall versions could allow an attacker to trick a user into visiting a crafted URL with the XSS payload. The attacker could gain access to sensitive browser-based information if the malicious script is executed on the victim’s browser.

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


ZLD V4.32~V5.31

ZLD V5.32


ZLD V4.50~V5.31

ZLD V5.32


ZLD V4.30~V5.31

ZLD V5.32


ZLD V4.30~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 Alessandro Sgreccia from Tecnical Service SRL for reporting the issue to us.

Revision histor

2022-12-06: Initial release