Description
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.
Problem types
CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Product status
References
github.com/...ecrets/security/advisories/GHSA-r2pg-r6h7-crf3
github.com/...ommit/6800989bdc12782ca2605d3b8bf7f2876a16551a
github.com/...l-secrets/external-secrets/releases/tag/v2.3.0