Urges customers to patch Netscreen devices immediately. Network equipment vendor Juniper has issued an urgent security alert for its Netscreen range of enterprise firewalls, after discovering "unauthorised code" in the device operating system that allows them to be fully compromised. According to Juniper chief information officer Bob Worrall, the code was discovered during an internal review of the ScreenOS operating system for the Netscreen firewalls. One vulnerability could be triggered to permit an attacker to log in via Secure Shell or telnet connections, and gain administrative privileges on Netscreen firewalls.