Argo CD: A Kustomize remote ref can run commands in the repo-server

Overview

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From 2.7.0 until 3.3.15, 3.4.10, 3.5.4, and 3.6.0-rc2, Kustomize passes ref or version query values from remote resource, base, or component URLs to git fetch without an end-of-options separator. A leading-hyphen value can be parsed as --upload-pack and execute a command inside argocd-repo-server when the remote uses a local transport such as file://. Git does not run the supplied command for an https:// remote. The local transport does not leave the pod, so blocking repo-server egress does not prevent the execution. The command runs as the repo-server user, can read repository credentials and other process-accessible data, and can return output through manifest-generation errors. An attacker can commit a Kustomization to a Git repository that an Application builds or upload 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. Kustomize 5.0.0 introduced acceptance of file://, whereas 4.5.7 rejects that transport; replacing the affected Kustomize with a newer version alone does not correct the missing option separator. This issue is fixed in versions 3.3.15, 3.4.10, 3.5.4, and 3.6.0-rc2.

Affected

• argo-cd >= 2.7.0, < 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.