Kubernetes NodeRestriction Vulnerability Lets Nodes Bypass Resource Allocation Authorization

A newly disclosed vulnerability in Kubernetes, tracked as CVE-2025-4563, enables nodes to bypass authorization checks for dynamic resource allocation.

This low-severity flaw (CVSS 2.7) affects specific versions of kube-apiserver and requires two conditions: the DynamicResourceAllocation feature gate (disabled by default) must be enabled, and clusters must utilize static pods.

The vulnerability allows compromised nodes to create unauthorized “mirror pods,” potentially leading to privilege escalation.

Vulnerability Mechanics and Attack Surface

The flaw resides in the NodeRestriction admission controller, which enforces security policies for node operations.

When the DynamicResourceAllocation The feature is active, the controller properly validates resource claims during pod status updates but fails to apply equivalent checks during pod creation.

This oversight enables an attacker-controlled node to:

1. Create malicious mirror pods via the Kubernetes API.
2. Attach unauthorized dynamic resources (e.g., GPU or FPGA allocations) to these pods.
3. Escalate privileges within the cluster environment.

Affected versions include kube-apiserver v1.32.0–v1.32.5 and v1.33.0–v1.33.1.

The risk is confined to clusters combining static pods with dynamic resource allocation—a configuration primarily seen in specialized hardware orchestration scenarios.

Mitigation Strategies and Patched Releases

To remediate CVE-2025-4563:

1. Upgrade immediately to patched versions: v1.32.6 or v1.33.2 for respective release branches.
2. Disable the feature gate if dynamic resource allocation is unused: text--feature-gates="DynamicResourceAllocation=false"
3. Audit static pod usage and restrict node credentials to least-privilege principles.

The Kubernetes project has released patches addressing the authorization gap, ensuring the NodeRestriction controller now validates resource claims identically during both pod creation and status updates.

Security Implications and Best Practices

While exploitation requires an already compromised node, this flaw underscores critical security practices:

• Avoid enabling alpha features like DynamicResourceAllocation in production unless rigorously tested.
• Monitor node credentials using tools like Kubernetes RBAC and audit logs.
• Isolate high-value resources (e.g., hardware accelerators) via namespaces and network policies.

Administrators should prioritize patching or disabling the vulnerable feature. For clusters requiring dynamic resource allocation, upgrading remains the only secure option.

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