Argo Workflows (controller, ArtifactGC.PodSpecPatch / template reference allow-list): The allow-list that is supposed

Impact

The allow-list that is supposed to force users onto admin-approved WorkflowTemplates only inspects top-level WorkflowSpec fields, so a podSpecPatch nested under ArtifactGC slips through untouched and is applied to the pod. A tenant who can submit a Workflow overrides the security settings the platform team pinned in the template - service account, security context, mounts - and runs with privileges they were never granted. Third bypass in the same allow-list, after CVE-2026-31892 and CVE-2026-42296.

Who can reach it

Any user or service account with permission to create Workflow objects in a namespace the controller watches. Works even when the controller runs with templateReferencing set to Strict or Secure.

What to do

Upgrade the workflow controller to 3.7.15 or 4.0.6 and restart it. Do not treat templateReferencing Strict as a boundary on its own - back it with a Kubernetes admission policy (Kyverno, Gatekeeper or ValidatingAdmissionPolicy) that rejects podSpecPatch, hostNetwork and serviceAccountName overrides on tenant-submitted Workflows.

References