{"id":"CVE-2026-34984","aliases":["GHSA-r2pg-r6h7-crf3","GO-2026-5602"],"url":"https://o3.security/vulnerability/CVE-2026-34984","summary":"External Secrets Operator has DNS exfiltration via getHostByName in its v2 template engine","details":"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.","published":"2026-04-14T01:48:41.166Z","modified":"2026-08-07T11:50:58.862941439Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/external-secrets/external-secrets","fixedVersion":"1.3.3-0.20260331202714-6800989bdc12"},{"ecosystem":"Go","name":"github.com/external-secrets/external-secrets","fixedVersion":null}],"fix":{"url":"https://github.com/external-secrets/external-secrets/commit/6800989bdc12782ca2605d3b8bf7f2876a16551a","label":"external-secrets/external-secrets@6800989"},"references":[{"type":"WEB","url":"https://github.com/external-secrets/external-secrets/releases/tag/v2.3.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34984.json"},{"type":"ADVISORY","url":"https://github.com/external-secrets/external-secrets/security/advisories/GHSA-r2pg-r6h7-crf3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34984"},{"type":"FIX","url":"https://github.com/external-secrets/external-secrets/commit/6800989bdc12782ca2605d3b8bf7f2876a16551a"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:50:58.862941439Z"}}