CVE-2026-34984 External Secrets Operator has DNS exfiltration via getHostByName in its v2 template engine

What is CVE-2026-34984?

CVE-2026-34984 is a high-severity vulnerability in external-secrets, published on 14 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official 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.

Weakness: CWE-200

Which versions are affected by CVE-2026-34984?

5 open source packages ship an affected version, including github.com/external-secrets/external-secrets. It affects 1 product.

Products include External-Secrets External Secrets Operator.

How do I fix CVE-2026-34984?

Upgrade github.com/external-secrets/external-secrets to 1.3.3-0.20260331202714-6800989bdc12 or later.

Is CVE-2026-34984 being exploited?

There is no known exploitation of CVE-2026-34984 in the wild and no public exploit code.

Other vulnerabilities in external-secrets

• CVE-2024-36540 Missing authorization in n/a Critical 9.8
• CVE-2026-22822 External Secrets Operator insecurely retrieves secrets through the getSecretKey templating function Critical 9.3
• CVE-2024-45041 External Secrets Operator vulnerable to privilege escalation High 8.3

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-r2pg-r6h7-crf3, GO-2026-5602, MINI-5c9j-974f-562w, MINI-xx2p-8qq7-9wfq.