Elastic Cloud on Kubernetes: Fleet Server Elasticsearch token written into the workload spec in cleartext

Impact

When ECK reconciles a Fleet Server that authenticates to Elasticsearch with a service account token, it embeds the live token directly in the generated pod/workload specification instead of referencing the Kubernetes Secret it already maintains for the other credentials. Kubernetes RBAC treats read access to workload specs as far less sensitive than read access to Secrets, so any principal that can list or get workloads in that namespace - a monitoring agent, a CI service account, a tenant with a namespace-scoped viewer role - walks off with a working Elasticsearch credential it was never granted. On a GPU fleet the Elastic stack is usually where job telemetry, audit and node logs land, so the token buys read or write access to the operational record of every tenant on the cluster. The exposure is passive and leaves no trace in Secret access audit logs.

Who can reach it

Any authenticated Kubernetes principal with read access to workload specifications (pods, StatefulSets) in the namespace where ECK manages the Fleet Server. No access to Kubernetes Secrets is required, and no cluster-admin rights.

What to do

Upgrade the ECK operator to 3.5.0 per Elastic advisory ESA-2026-113; the operator pod restarts and re-reconciles the affected resources, which rolls the Fleet Server workload but does not require draining GPU nodes. Treat any service account token that was already rendered into a workload spec as disclosed and rotate it in Elasticsearch after upgrading - the upgrade stops new leakage but does not invalidate tokens already read.

References

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