CVE-2026-26287

Summary

A bug in the webhook generator initialization order incorrectly cleared the label-enforcement flag (EnforceLabels) after it was set, resulting in the provider-side check for external-secrets.io/type=webhook being skipped (and the operation to succeed while it should have failed with secret does not contain needed label 'external-secrets.io/type: webhook'. Update secret label to use it with webhook.

Impact

A user with the permission to create webhook generator can set the webhook generator to a victim' secret (which was not previously labelled for webhook's use), and exfiltrate it to a malicious URL.

Mitigations

Until you upgrade, you can reduce risk by:

• disabling webhook generators if not needed (or denying generators.external-secrets.io/v1alpha1 Webhook via an admission policy);
• restricting RBAC: limit who can create generators of kind Webhook;
• enforcing an admission policy (OPA Gatekeeper / Kyverno) requiring referenced secrets to be labeled external-secrets.io/type=webhook;
• restricting egress from external-secrets controller pods to an allowlist (kubernetes NetworkPolicy / service mesh egress policy).

References

• PR #5901 (fix: webhook initialization order)