CVE-2026-34984
External Secrets Operator reads information from a third-party service and automatically injects the values as Kubernetes Secrets.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/external-secrets/external-secrets | < 1.3.3-0.20260331202714-6800989bdc12 | 1.3.3-0.20260331202714-6800989bdc12 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| External-Secrets | External Secrets Operator | before 2.3.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-r2pg-r6h7-crf3
- https://github.com/external-secrets/external-secrets/security/advisories/GHSA-r2pg-r6h7-crf3
- https://github.com/external-secrets/external-secrets/commit/6800989bdc12782ca2605d3b8bf7f2876a16551a
- https://github.com/external-secrets/external-secrets/releases/tag/v2.3.0
- https://nvd.nist.gov/vuln/detail/CVE-2026-34984