A security vulnerability exists in the Sealed Secrets controller's unauthenticated POST endpoints. By submitting a modified payload containing custom Go template logic in spec.template.data, an attacker with internal network access can abuse the handler as a decryption oracle to recover the full plaintext of any sealed secret.
The POST /v1/verify and /v1/rotate handlers call Unseal() to decrypt target secrets, then render any Go templates found in spec.template.data.* using the decrypted payload as the evaluation context (pkg/apis/sealedsecrets/v1alpha1/sealedsecret_expansion.go). Errors encountered during template execution are directly reflected in the resulting HTTP response status codes.
Missing AEAD label binding: the spec.template.data field is omitted from the AEAD authenticated-data label binding ciphertext to metadata. As a result, an attacker can copy a target's valid metadata and encryptedData verbatim, satisfying AEAD decryption and label validation, while freely replacing spec.template.data with arbitrary template logic.
Side-channel oracle: template execution errors map directly to HTTP response codes. HTTP 200 (OK) indicates template execution succeeded; HTTP 409 (Conflict) indicates template execution failed (e.g. via {{ fail \"...\" }}).
By injecting conditional statements such as {{ if eq (substr 0 1 .password) \"S\" }}ok{{ else }}{{ fail \"x\" }}{{ end }}, an attacker receives an HTTP 200 status when a character guess is correct and an HTTP 409 when it is incorrect. This differential response leaks one character-equality bit per request, allowing full secret extraction over successive queries.
Attack vector & prerequisites: unauthenticated; requires network access to the controller's internal service port (:8080). Although this service is not exposed to the public internet by default, it is accessible to any pod within the Kubernetes cluster or via a kubectl port-forward connection.
"}],"value":"A security vulnerability exists in the Sealed Secrets controller's unauthenticated POST endpoints. By submitting a modified payload containing custom Go template logic in spec.template.data, an attacker with internal network access can abuse the handler as a decryption oracle to recover the full plaintext of any sealed secret.\n\n\n\nThe POST /v1/verify and /v1/rotate handlers call Unseal() to decrypt target secrets, then render any Go templates found in spec.template.data.* using the decrypted payload as the evaluation context (pkg/apis/sealedsecrets/v1alpha1/sealedsecret_expansion.go). Errors encountered during template execution are directly reflected in the resulting HTTP response status codes.\n\n\n\nMissing AEAD label binding: the spec.template.data field is omitted from the AEAD authenticated-data label binding ciphertext to metadata. As a result, an attacker can copy a target's valid metadata and encryptedData verbatim, satisfying AEAD decryption and label validation, while freely replacing spec.template.data with arbitrary template logic.\n\n\n\nSide-channel oracle: template execution errors map directly to HTTP response codes. HTTP 200 (OK) indicates template execution succeeded; HTTP 409 (Conflict) indicates template execution failed (e.g. via {{ fail \"...\" }}).\n\n\n\nBy injecting conditional statements such as {{ if eq (substr 0 1 .password) \"S\" }}ok{{ else }}{{ fail \"x\" }}{{ end }}, an attacker receives an HTTP 200 status when a character guess is correct and an HTTP 409 when it is incorrect. This differential response leaks one character-equality bit per request, allowing full secret extraction over successive queries.\n\n\n\nAttack vector & prerequisites: unauthenticated; requires network access to the controller's internal service port (:8080). Although this service is not exposed to the public internet by default, it is accessible to any pod within the Kubernetes cluster or via a kubectl port-forward connection."}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.2,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"HIGH","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"providerMetadata":{"dateUpdated":"2026-09-15T09:16:59.460Z","orgId":"dcf2e128-44bd-42ed-91e8-88f912c1401d","shortName":"vmware"},"references":[{"url":"https://github.com/bitnami/sealed-secrets/security/advisories/GHSA-qj4p-m373-p2wg"},{"url":"https://github.com/bitnami/sealed-secrets"}],"title":"Sealed Secrets: decryption oracle via Go template injection in unauthenticated controller endpoints"}},"cveMetadata":{"assignerOrgId":"dcf2e128-44bd-42ed-91e8-88f912c1401d","assignerShortName":"vmware","cveId":"CVE-2026-59341","datePublished":"2026-09-15T09:16:59.460Z","dateReserved":"2026-07-04T18:14:34.672Z","dateUpdated":"2026-09-15T17:28:36.930Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-15 10:17:05","lastModifiedDate":"2026-09-15 18:17:26","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"security@vmware.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N","baseScore":4.2,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"HIGH","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"NONE"},"exploitabilityScore":0.5,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-15T17:27:25.731287Z","id":"CVE-2026-59341","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"59341","Ordinal":"1","Title":"Sealed Secrets: decryption oracle via Go template injection in u","CVE":"CVE-2026-59341","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"59341","Ordinal":"1","NoteData":"A security vulnerability exists in the Sealed Secrets controller's unauthenticated POST endpoints. By submitting a modified payload containing custom Go template logic in spec.template.data, an attacker with internal network access can abuse the handler as a decryption oracle to recover the full plaintext of any sealed secret.\n\n\n\nThe POST /v1/verify and /v1/rotate handlers call Unseal() to decrypt target secrets, then render any Go templates found in spec.template.data.* using the decrypted payload as the evaluation context (pkg/apis/sealedsecrets/v1alpha1/sealedsecret_expansion.go). Errors encountered during template execution are directly reflected in the resulting HTTP response status codes.\n\n\n\nMissing AEAD label binding: the spec.template.data field is omitted from the AEAD authenticated-data label binding ciphertext to metadata. As a result, an attacker can copy a target's valid metadata and encryptedData verbatim, satisfying AEAD decryption and label validation, while freely replacing spec.template.data with arbitrary template logic.\n\n\n\nSide-channel oracle: template execution errors map directly to HTTP response codes. HTTP 200 (OK) indicates template execution succeeded; HTTP 409 (Conflict) indicates template execution failed (e.g. via {{ fail \"...\" }}).\n\n\n\nBy injecting conditional statements such as {{ if eq (substr 0 1 .password) \"S\" }}ok{{ else }}{{ fail \"x\" }}{{ end }}, an attacker receives an HTTP 200 status when a character guess is correct and an HTTP 409 when it is incorrect. This differential response leaks one character-equality bit per request, allowing full secret extraction over successive queries.\n\n\n\nAttack vector & prerequisites: unauthenticated; requires network access to the controller's internal service port (:8080). Although this service is not exposed to the public internet by default, it is accessible to any pod within the Kubernetes cluster or via a kubectl port-forward connection.","Type":"Description","Title":"Sealed Secrets: decryption oracle via Go template injection in u"}]}}}