The UDP implementation in Linux 2.4.x kernels keeps the IP Identification field at 0 for all non-fragmented packets, which could allow remote attackers to determine that a target system is running Linux.

The encrypted loop device in Linux kernel 2.4.10 and earlier does not authenticate the entity that is encrypting data, which allows local users to modify encrypted data without knowing the key.

The MAC module in Netfilter in Linux kernel 2.4.1 through 2.4.11, when configured to filter based on MAC addresses, allows remote attackers to bypass packet filters via small packets.

ptrace in Linux 2.2.x through 2.2.19, and 2.4.x through 2.4.9, allows local users to gain root privileges by running ptrace on a setuid or setgid program that itself calls an unprivileged program, such as newgrp.