CVE-2001-1135: ZyXEL Prestige 642R and 642R-I routers do not filter the routers' Telnet and FTP ports on the external WAN...

Security readout for executives and security teams

This old ZyXEL router issue could let someone already on the internal network change router settings through Telnet or FTP if they know the password. The business risk is mainly legacy network equipment control: route changes, outage, or weakened perimeter settings. Exposure is most likely in environments still running ZyXEL Prestige 642R or 642R-I ADSL routers, especially with Telnet or FTP administration enabled and weak, default, or shared administrator passwords. Treat this as a legacy equipment governance issue rather than an emergency. Prioritize discovery and retirement if these routers still exist, because management-plane compromise can disrupt connectivity or weaken network controls. Mitigation focus: Inventory for ZyXEL Prestige 642R and 642R-I routers.; Check vendor or historical advisories for firmware or configuration guidance.; Remove or replace unsupported legacy routers where feasible..

Prepared

Jul 1, 2026, 07:29 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.