External Secrets Operator reads information from a third-party service and automatically injects the values as Kubernetes Secrets. Versions 2.2.0 and below contain a vulnerability in runtime/template/v2/template.go where the v2 template engine removes env and expandenv from Sprig's TxtFuncMap() but leaves the getHostByName function accessible to user-controlled templates. Since ESO executes templates within the controller process, an attacker who can create or update templated ExternalSecret resources can invoke controller-side DNS lookups using secret-derived values. This creates a DNS exfiltration primitive, allowing fetched secret material to be leaked via DNS queries without requiring direct outbound network access from the attacker's workload. The impact is a confidentiality issue, particularly in environments where untrusted or lower-trust users can author templated ExternalSecret resources and the controller has DNS resolution capability. This issue has been fixed in version 2.3.0.

External Secrets Operator reads information from a third-party service and automatically injects the values as Kubernetes Secrets. Starting in version 0.20.2 and prior to version 1.2.0, the `getSecretKey` template function, while introduced for senhasegura Devops Secrets Management (DSM) provider, has the ability to fetch secrets cross-namespaces with the roleBinding of the external-secrets controller, bypassing our security mechanisms. This function was completely removed in version 1.2.0, as everything done with that templating function can be done in a different way while respecting External Secrets Operator's safeguards As a workaround, use a policy engine such as Kubernetes, Kyverno, Kubewarden, or OPA to prevent the usage of `getSecretKey` in any ExternalSecret resource.

External Secrets Operator is a Kubernetes operator that integrates external secret management systems. The external-secrets has a deployment called default-external-secrets-cert-controller, which is bound with a same-name ClusterRole. This ClusterRole has "get/list" verbs of secrets resources. It also has path/update verb of validatingwebhookconfigurations resources. This can be used to abuse the SA token of the deployment to retrieve or get ALL secrets in the whole cluster, capture and log all data from requests attempting to update Secrets, or make a webhook deny all Pod create and update requests. This vulnerability is fixed in 0.10.2.

Insecure permissions in external-secrets v0.9.16 allows attackers to access sensitive data and escalate privileges by obtaining the service account's token.