fasttrack p2p, as used in (1) KaZaA, (2) grokster, and (3) morpheus allows remote attackers to spoof other users by modifying the username and network information in the message header.

fasttrack p2p, as used in (1) KaZaA before 1.5, (2) grokster, and (3) morpheus allows remote attackers to cause a denial of service (memory exhaustion) via a series of client-to-client messages, which pops up new windows per message.