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GHSA-jv3w-x3r3-g6rm

MediumCVSS 6.6 / 10
Published Dec 9, 2025·Last modified Mar 24, 2026
Affected Components(0)

No affected components available

Description

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.

Risk Scores
Base Score
6.6

The vulnerability requires local access to the device to be exploited. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
6.1

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.12%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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