CNA Plugins Portmap nftables backend can intercept non-local traffic

Open Source Vulnerabilities GHSA-jv3w-x3r3-g6rm

### 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.

Open Source Vulnerabilities GO-2025-4222

CNA Plugins Portmap nftables backend can intercept non-local traffic in github.com/containernetworking/plugins

Open Source Vulnerabilities CVE-2025-67499

The CNI portmap plugin allows containers to emulate opening a host port, forwarding that traffic to the container. Versions 1.6.0 through 1.8.0 inadvertently forward all traffic with the same destination port as the host port when the portmap plugin is configured with the nftables backend, thus ignoring the destination IP. This includes traffic not intended for the node itself, i.e. traffic to containers hosted on the node. Containers 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. This issue is fixed in version 1.9.0. To workaround, configure the portmap plugin to use the iptables backend. It does not have this vulnerability.