CVE-2026-75033

Rancher Manager propagated Project Secrets into a namespace based solely on the namespace's `field.cattle.io/projectId` annotation, without verifying that the referenced project belonged to the same downstream cluster (CWE-639, authorization bypass via user-controlled key). A user with permission to create namespaces on one managed cluster can set that annotation to a project ID from a different cluster, causing Rancher to copy that project's secrets into a namespace under their control. The attacker gains cross-tenant, cross-cluster disclosure of secret material — high confidentiality impact with no integrity or availability impact, reflected in the CVSS 3.1 score of 7.7 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N). All Rancher releases before 2.15.1 are affected, with multi-cluster deployments that grant namespace-creation rights to low-privilege users the most exposed. No public proof-of-concept is known, the flaw is not in CISA's KEV, and EPSS estimates roughly a 0.2% chance of exploitation within 30 days.

What to do: Upgrade Rancher to version 2.15.1 or later. Until patched, audit namespaces for `field.cattle.io/projectId` annotations that reference projects on other clusters, limit namespace-creation permissions to trusted users, and treat secrets held in other clusters' projects as potentially disclosed, rotating any high-value credentials found there.