A reflected cross-site scripting (XSS) vulnerability in the CGI program "dynamic_script.cgi" of Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V4.16 through V5.38, and USG20(W)-VPN series firmware versions from V4.16 through V5.38 could allow an attacker to trick a user into visiting a crafted URL with the XSS payload. The attacker could obtain browser-based information if the malicious script is executed on the victim’s browser.