A flaw was found in hypershift-addon-operator. The buildOtherInstallFlags() function in pkg/install/hypershift.go reads arbitrary key-value pairs from the hypershift-operator-install-flags ConfigMap and appends them unsanitized as CLI arguments to the hypershift install Job. A hub-cluster namespace administrator with write access to this ConfigMap can inject arbitrary flags into the privileged install Job, enabling arbitrary image pull and cluster-admin code execution on managed spoke clusters.

The vulnerable code path is: pkg/install/hypershift.go lines 428-506 (buildOtherInstallFlags) and pkg/install/install_job.go lines 19-41 (Job construction). The install Job runs with elevated privileges sufficient to deploy the HyperShift operator on spoke clusters.

Attack scenario: An attacker with namespace-admin privileges on the hub cluster writes crafted entries to the hypershift-operator-install-flags ConfigMap. When the addon-manager reconciles, it invokes buildOtherInstallFlags() which blindly converts ConfigMap data entries into --key=value flags passed to the hypershift install command. The attacker can inject flags such as --image-refs to pull a malicious operator image, achieving cluster-admin execution on the target spoke cluster.

This vulnerability was identified during an authorized security assessment (Project Glasswing). Execution was proven in a controlled test environment.