An issue was discovered in the iptables firewall module in OpenStack Neutron before 10.0.8, 11.x before 11.0.7, 12.x before 12.0.6, and 13.x before 13.0.3. By setting a destination port in a security group rule along with a protocol that doesn't support that option (for example, VRRP), an authenticated user may block further application of security group rules for instances from any project/tenant on the compute hosts to which it's applied. (Only deployments using the iptables security group driver are affected.)