Argo CD: A Kustomize Helm config home can run commands in the repo-server

Overview

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From 2.1.0 until 3.3.15, 3.4.10, 3.5.4, and 3.6.0-rc2, when an operator has enabled --enable-helm for kustomize build, helmGlobals.configHome can point Helm's config and data directories at a repository-controlled location. Helm automatically loads a downloader plugin from <configHome>/.data/plugins without a separate plugin-install step and executes its program inside argocd-repo-server when a helmCharts repository URL uses the plugin's protocol. The command runs as the repo-server user and can read repository credentials and other process-accessible data. An attacker can commit the Kustomization and plugin to a Git repository that an Application builds or upload the files through POST /api/v1/applications/manifestsWithFiles, also exposed by argocd app diff --local --server-side-generate. The upload path requires only Application get permission on an existing Application, without Application update or sync permission or repository write access. Both delivery paths require prior operator enablement of --enable-helm; deployments that do not enable it are not affected. Kustomize 4.1.0 first passed helmGlobals.configHome through to Helm. This issue is fixed in versions 3.3.15, 3.4.10, 3.5.4, and 3.6.0-rc2.

Affected

• argo-cd >= 2.1.0, < 3.3.15
• argo-cd >= 3.4.0-rc1, < 3.4.10
• argo-cd >= 3.5.0-rc1, < 3.5.4
• argo-cd >= 3.6.0-rc1, < 3.6.0-rc2

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.