Runtime Supply Chain Verification using the Node Resource Interface (NRI)

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The widely used container supply chain verification tools today operate at the Kubernetes API layer as admission webhooks (such as Kyverno, OPA Gatekeeper, and Sigstore Policy Controller). They intercept pod creation, check signatures and attestations, and either admit or reject the pod.

However, admission webhooks depend on explicit configuration and network connectivity. Misconfigured namespace selectors can silently skip verification. An admission webhook outage forces a choice between cluster lockup and silent bypass. Static pods and direct kubelet API access bypass admission webhooks entirely.

What if verification moved one layer lower—to the container runtime itself—where every container must pass through regardless of how it was scheduled?

That is what the Supply Chain NRI Plugin does. Originally proposed as an in-tree CRI-O feature, community feedback favored a plugin approach: it works with both CRI-O and containerd, ships on its own release cycle, and keeps the runtime’s critical path simple.

The Gap Below the API Server

Kubernetes documents these bypass paths explicitly. For example, static pods are managed directly by the kubelet. Even when their mirror pod fails admission, the container still runs. A static pod with an invalid namespace name becomes invisible to the API entirely. None of these containers pass through admission webhooks, so any image verification configured at that layer simply does not apply.

These are not theoretical risks. Techniques using mutating webhook manipulation to confuse validating webhooks have been disclosed, meaning …

Vollständiger Originalartikel ↗

• Betroffenheit im eigenen Stack prüfen: Versionen/Komponenten abgleichen.
• Originalquelle / Hersteller-Advisory lesen: https://www.cncf.io/blog/2026/07/30/runtime-supply-chain-verification-using-the-node-resource-interface-nri/
• Verfügbaren Patch oder Workaround einspielen und dokumentieren.