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GHSA-r2pg-r6h7-crf3

External Secrets Operator has DNS-based secret exfiltration via getHostByName in External Secrets v2 template engine

Source: GitHub Advisory Database (reviewed) High CVE-2026-34984

Packages

EcosystemPackageAffectedFixed in
Go github.com/external-secrets/external-secrets < 1.3.3-0.20260331202714-6800989bdc12 1.3.3-0.20260331202714-6800989bdc12
Go github.com/external-secrets/external-secrets >= 2.0.0, <= 2.2.0 no fix listed

Details

As written in the advisory (Markdown source, shown as plain text).

## Summary The v2 template engine in `runtime/template/v2/template.go` imports Sprig’s `TxtFuncMap()` and removes `env` and `expandenv`, but leaves `getHostByName` available to user-controlled templates. Because ESO executes templates inside the controller process, an attacker who can create or update templated ExternalSecret resources can trigger controller-side DNS lookups using secret-derived values, creating a DNS exfiltration primitive. ### Impact This is a confidentiality issue. In environments where untrusted or lower-trust users can author templated ExternalSecret resources and the controller can perform DNS resolution, fetched secret material can be exfiltrated through DNS without requiring direct outbound access from the attacker’s workload.

References

External links from the advisory. They lead to third-party sites.