nasty bug for iptables and a 2.6 kernel

Details are here. Basically, if you're using iptables with --tcp-option , a specially formed packet will put the kernel in an infinite loop. The link explains the vulnerability in depth.
Happily, the fix involves changing "char" on line 1461 of net/ipv4/netfilter/ip_tables.c[/b] to "u_int8_t" .

Edit: The current 2.6 kernel 2.6.7, so 2.6.0 through 2.6.7 are vulnerable.