KEDA: Privilege escalation from namespace admin to cluster admin via KEDA TriggerAuthentication

KEDA is a Kubernetes-based Event Driven Autoscaling component. In version 2.20.2 and earlier, a namespace administrator who can create TriggerAuthentication and ScaledObject resources can set hashiCorpVault.address to a tenant-controlled endpoint and select Kubernetes authentication without an explicit credential. KEDA then uses the operator pod's projected ServiceAccount token and sends it to that endpoint as a Vault login credential. The JWT-shape filter from the prior CVE-2025-68476 remediation accepts the operator token because its subject is a Kubernetes ServiceAccount, so the attacker can obtain the operator's cluster-wide permissions, including broad Secret reads and workload or admission-related operations. This vulnerability is fixed in 2.21.0.