Smoothwall Express 3.1-SP4-polar-x86_64-update9 contains multiple reflected cross-site scripting vulnerabilities in the dhcp.cgi script that allow attackers to inject malicious scripts through multiple parameters. Attackers can submit POST requests to dhcp.cgi with script payloads in parameters such as BOOT_SERVER, BOOT_FILE, BOOT_ROOT, START_ADDR, END_ADDR, DNS1, DNS2, NTP1, NTP2, WINS1, WINS2, DEFAULT_LEASE_TIME, MAX_LEASE_TIME, DOMAIN_NAME, NIS_DOMAIN, NIS1, NIS2, STATIC_HOST, STATIC_DESC, STATIC_MAC, and STATIC_IP to execute arbitrary JavaScript in user browsers.