The experimental IP packet queuing feature in Netfilter / IPTables in Linux kernel 2.4 up to 2.4.19 and 2.5 up to 2.5.31, when a privileged process exits and network traffic is not being queued, may allow a later process with the same Process ID (PID) to access certain network traffic that would otherwise be restricted.

The Linux kernel 2.4.20 and earlier, and 2.5.x, when running on x86 systems, allows local users to cause a denial of service (hang) via the emulation mode, which does not properly clear TF and NT EFLAGs.

The d_path function in Linux kernel 2.2.20 and earlier, and 2.4.18 and earlier, truncates long pathnames without generating an error, which could allow local users to force programs to perform inappropriate operations on the wrong directories.

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 Network Address Translation (NAT) capability for Netfilter ("iptables") 1.2.6a and earlier leaks translated IP addresses in ICMP error messages.

IRC connection tracking helper module in the netfilter subsystem for Linux 2.4.18-pre9 and earlier does not properly set the mask for conntrack expectations for incoming DCC connections, which could allow remote attackers to bypass intended firewall restrictions.

The ugidd RPC interface, by design, allows remote attackers to enumerate valid usernames by specifying arbitrary UIDs that ugidd maps to local user and group names.