CVE-2026-50563: Fission Container Executor Function PodSpec Injection Leading to Node Escape

Synopsis

A PodSpec injection vulnerability in Fission, the Kubernetes-native serverless framework, allows an authenticated tenant to supply arbitrary pod specifications through the Function.spec.podspec field in the Container Executor path. The executor merges the tenant-controlled input directly into its own pod spec before creating a Deployment, and the attack is reachable over the network with only a low-privilege account. Successful exploitation enables a full node escape: the attacker gains the ability to read, modify, and disrupt workloads and data across the underlying Kubernetes node. No fix version has been published yet; HarborGuard is tracking the advisory for patch availability.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The vulnerable Fission API endpoint is exposed over the network, so an attacker must be able to reach the service remotely.

• AuthenticationRequired

  A low-privilege tenant account is sufficient; no administrative credentials are needed to supply a malicious pod spec.

• Victim interactionNot required

  No victim action is needed; the attacker submits the malicious Function spec directly to the API without involving another user.

• Attack complexityDetail

  Exploitation is reliable and condition-free; no race conditions or special environmental factors are required to inject the pod spec.

Blast Radius

• Reads secrets, service account tokens, and environment variables belonging to other workloads running on the same Kubernetes node.
• Modifies or deletes pod configurations and persisted data accessible from the node, including volumes mounted by co-located workloads.
• Crashes or disrupts unrelated services on the node by exhausting shared resources or terminating co-located containers.
• Escapes the container boundary entirely and gains execution-level access to the underlying node host, enabling lateral movement across the cluster.