GHSA-jv3w-x3r3-g6rm CNA Plugins Portmap nftables backend can intercept non-local traffic

• Go github.com/containernetworking/plugins: >= 1.6.0, < 1.9.0 → fixed in 1.9.0

Background The CNI `portmap` plugin allows containers to emulate opening a host port, forwarding that traffic to the container. For example, if a host has the IP 198.51.100.42, a container may request that all packets to `198.51.100.42:53` be forwarded to the container's network. Vulnerability When the `portmap` plugin is configured with the `nftables` backend, it inadvertently forwards all traffic with the same destination port as the host port, ignoring the destination IP. This includes traffic not intended for the node itself, i.e. traffic to containers hosted on the node. In the given example above, traffic destined to port 53 but for a _separate container_ would still be captured and forwarded, even though it was not destined for the host. Impact Containers (i.e. kubernetes pods) that request HostPort forwarding can intercept all traffic destined for that port. This requires that the `portmap` plugin be explicitly configured to use the `nftables` backend. (The `iptables` backend is the default.) Patches This is fixed as of CNI plugins v1.9.0 Workarounds Configure the `portmap` plugin to use the `iptables` backend. It does not have this vulnerability.