CVE-2026-22728: Sealed Secrets for Kubernetes: Rotate API Allows Scope Widening from Strict/Namespace-Wide to Cluster-Wide via Untrusted Template Annotations

This report shows a scope-widening issue in the rotate (re-encrypt) flow: the output scope can be derived from untrusted spec.template.metadata.annotations on the input sealed secret.

If a victim sealed secret is strict- or namespace-scoped, an attacker who can submit it to the rotate endpoint can set sealedsecrets.bitnami.com/cluster-wide=true in the template metadata and receive a rotated sealed secret that is cluster-wide, enabling retargeting (metadata.name/metadata.namespace) and unsealing to recover the victim plaintext.