Description

A flaw was found in Rancher Manager. Project Secrets were propagated into a namespace based only on its `field.cattle.io/projectId` annotation, without verifying that the referenced project belonged to the same downstream cluster. A user able to create namespaces on one cluster could set the annotation to a project ID from another cluster and have that project's secrets copied into a namespace under their control. This issue affects Rancher: before 2.15.1.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.7",
  "pubDate": "2026-09-03T15:17:32.873Z",
  "pubdate": "2026-09-03T15:17:32.873Z",
  "executiveSummary": "A critical authorization vulnerability exists in Rancher Manager where project-level secrets are improperly propagated to user-controlled namespaces. The vulnerability stems from insufficient validation of the 'field.cattle.io/projectId' annotation, which determines secret distribution across downstream clusters.\nBy manipulating this annotation, a malicious actor capable of creating namespaces within one cluster can gain unauthorized access to sensitive secrets belonging to projects located in a completely different, potentially higher-privileged downstream cluster.\nThis flaw effectively facilitates cross-cluster secret exfiltration, leading to unauthorized access to credentials, API keys, or certificates stored within Rancher Projects. The vulnerability affects Rancher Manager versions prior to 2.15.1.\nThe exploitation requirement is limited to the ability to create namespaces in a cluster managed by the affected Rancher instance. Successful exploitation grants attackers unauthorized read access to sensitive environment data, potentially leading to privilege escalation, lateral movement, or compromise of services secured by the affected secrets.",
  "technicalDetails": "The vulnerability resides in the Rancher Manager secret synchronization controller, which is responsible for propagating Project Secrets to associated namespaces. The mechanism relies on the presence of the 'field.cattle.io/projectId' annotation to identify which secrets should be mirrored into a specific namespace.\nThe root cause is a failure in the authorization logic within the propagation controller to enforce cross-cluster boundary checks. Specifically, the controller performs a lookup based solely on the provided Project ID without verifying whether the identified project exists within the same cluster context as the requesting namespace.\nThe attack flow proceeds as follows: First, an authenticated user with permission to manage namespaces in a target downstream cluster creates a new namespace. Second, the user injects the 'field.cattle.io/projectId' annotation into the new namespace metadata, setting the value to an arbitrary Project ID discovered or guessed from a separate downstream cluster managed by the same Rancher instance.\nThe synchronization controller, upon observing the annotation, attempts to reconcile the requested project resources. Because the controller lacks a security check to confirm that the referenced project matches the namespace's cluster domain, it proceeds to fetch the secrets associated with that Project ID.\nThese secrets are then automatically replicated into the attacker-controlled namespace. The victim secrets become readable to the attacker through standard Kubernetes API calls to list or describe secrets within their namespace.\nThis behavior represents an insecure direct object reference or an authorization bypass where the system assumes the user-supplied annotation is authoritative and inherently trusted. This vulnerability does not require administrative privileges on the target cluster, provided the attacker has basic namespace creation rights in any cluster governed by the Rancher Manager.\nPost-exploitation impact is severe, as it allows for the extraction of sensitive information that should be logically isolated by cluster and project boundaries. This bypasses the multi-tenancy security model implemented by Rancher, enabling horizontal movement across managed infrastructure."
}