Argo Workflows versions prior to 3.7.15 and 4.0.6 contain an improper access control vulnerability (CWE-284) due to incomplete allow-listing in the validation of user overrides in WorkflowSpec. The validation functions only inspect top-level fields and allow the ArtifactGC field wholesale, which contains a PodSpecPatch sub-field. This sub-field's contents are passed unmodified to the pod spec patching function, enabling a user to inject arbitrary strategic merge patches into the artifact garbage collection pod. This can include privileged container settings, hostPath volumes, arbitrary images and commands, and host networking, defeating the intended security restrictions of Strict or Secure template referencing modes. The vulnerability is addressed by fixes in versions 3.7.15 and 4.0.6.

An attacker with permission to submit workflows can escalate privileges by injecting arbitrary pod specification patches into the artifact garbage collection pod. This can lead to running containers with elevated privileges, access to host volumes, and network configurations that bypass security restrictions. This undermines the security model of Strict/Secure workflow template referencing, potentially allowing unauthorized code execution or access to the underlying Kubernetes host environment.

Upgrade to argoproj argo-workflows version 3.7.15 or 4.0.6 or later, where this vulnerability is fixed. Patch status is confirmed by the vendor advisory stating these versions contain the fix. No other mitigations are indicated.