CVE-2026-34984
Severity CVSS v4.0:
HIGH
Type:
CWE-200
Information Leak / Disclosure
Publication date:
14/04/2026
Last modified:
22/04/2026
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.
Impact
Base Score 4.0
7.10
Severity 4.0
HIGH
Base Score 3.x
6.50
Severity 3.x
MEDIUM
Vulnerable products and versions
| CPE | From | Up to |
|---|---|---|
| cpe:2.3:a:external-secrets:external_secrets_operator:*:*:*:*:*:*:*:* | 2.3.0 (excluding) |
To consult the complete list of CPE names with products and versions, see this page