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.
No analysis available yet.
Remediation
No remediation available yet.
Tracking
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Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-r2pg-r6h7-crf3 | External Secrets Operator has DNS-based secret exfiltration via getHostByName in External Secrets v2 template engine |
References
History
Tue, 14 Apr 2026 02:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | External Secrets Operator has DNS exfiltration via getHostByName in its v2 template engine | |
| Weaknesses | CWE-200 | |
| References |
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| Metrics |
cvssV4_0
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Subscriptions
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-04-14T01:48:41.166Z
Reserved: 2026-03-31T19:38:31.617Z
Link: CVE-2026-34984
No data.
Status : Received
Published: 2026-04-14T03:16:08.530
Modified: 2026-04-14T03:16:08.530
Link: CVE-2026-34984
No data.
OpenCVE Enrichment
No data.
Weaknesses
Github GHSA