CVE-2026-6388: Argocd-image-updater: argocd image updater: cross-namespace privilege escalation via insufficient namespace validation

A flaw was found in ArgoCD Image Updater. This vulnerability allows an attacker, with permissions to create or modify an ImageUpdater resource in a multi-tenant environment, to bypass namespace boundaries. By exploiting insufficient validation, the attacker can trigger unauthorized image updates on applications managed by other tenants. This leads to cross-namespace privilege escalation, impacting application integrity through unauthorized application updates.