Published: 15 February 2014
extensions/libxt_tcp.c in iptables through 1.4.21 does not match TCP SYN+FIN packets in --syn rules, which might allow remote attackers to bypass intended firewall restrictions via crafted packets. NOTE: the CVE-2012-6638 fix makes this issue less relevant.
This is an iptables userspace issue. A kernel CVE may also be assigned, but it will be under a different CVE identifier.
There is no available fix for this issue for iptables, and changing this would result in an unexpected change in behaviour. We will not be fixing this in Ubuntu stable releases, marking as ignored.