CVE-2026-75033: 
Rancher vulnerability analysis and mitigation

CVE-2026-75033 is an authorization bypass vulnerability in SUSE Rancher Manager where Project Secrets are propagated to namespaces based solely on the field.cattle.io/projectId annotation without verifying that the referenced project belongs to the same downstream cluster. An authenticated user with namespace creation permissions on one cluster can set this annotation to a project ID from a different cluster, causing that project's secrets to be copied into a namespace under their control. All Rancher versions before 2.15.1 are affected. The vulnerability carries a CVSS v3.1 base score of 7.7 (High) (Rancher v2.15.1 Release, Feedly).

The root cause is an authorization bypass through a user-controlled key (CWE-639): Rancher's project-scoped secretsController trusts the field.cattle.io/projectId annotation on a namespace at face value when deciding which Project Secrets to propagate, without cross-checking that the annotated project ID belongs to the same downstream cluster as the namespace. An attacker with low-privilege access (authenticated, with namespace creation rights on any downstream cluster) can craft a namespace with an annotation pointing to a project on a different cluster, triggering the controller to copy that foreign project's secrets into the attacker-controlled namespace. No user interaction is required, and the attack is conducted over the network (Rancher v2.15.1 Release, Feedly).

Successful exploitation results in unauthorized disclosure of Project Secrets from clusters the attacker does not have legitimate access to, representing a high confidentiality impact with no integrity or availability impact. Secrets exposed may include credentials, API keys, certificates, or other sensitive configuration data stored as Kubernetes secrets within Rancher projects. In multi-tenant or multi-cluster Rancher environments, this could enable lateral movement between clusters by leveraging leaked credentials (Rancher v2.15.1 Release, Feedly).

No public proof-of-concept exploit code or in-the-wild exploitation has been reported for CVE-2026-75033. The NVD SSVC assessment classifies exploitation as "none" at time of publication. The EPSS score is approximately 0.205%, indicating a low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires an authenticated user account with namespace creation permissions on at least one downstream cluster (Feedly).

1. Reconnaissance: Identify a Rancher environment running a version prior to 2.15.1 with multiple downstream clusters. Obtain or possess an authenticated account with namespace creation permissions on at least one downstream cluster.
2. Identify target project: Enumerate project IDs from other downstream clusters (e.g., via the Rancher API or UI) to identify a project containing secrets of interest. Project IDs follow the format c-<clusterID>:p-<projectID>.
3. Create a malicious namespace: On the cluster where the attacker has namespace creation rights, create a new namespace and set the field.cattle.io/projectId annotation to the project ID from the target cluster (e.g., field.cattle.io/projectId: c-targetcluster:p-targetproject).
4. Trigger secret propagation: The Rancher secretsController detects the annotation and propagates Project Secrets from the referenced project into the newly created namespace without validating cluster ownership.
5. Harvest secrets: Read the propagated Kubernetes secrets from the attacker-controlled namespace using standard kubectl get secrets -n <namespace> or equivalent API calls (Rancher v2.15.1 Release, Feedly).

• Kubernetes Audit Logs: Namespace creation events where the field.cattle.io/projectId annotation references a project ID from a different cluster than the one being operated on.
• Rancher Controller Logs: Unexpected secret propagation events in the secretsController logs where the source project cluster ID does not match the destination namespace's cluster ID.
• Kubernetes API: Presence of Project Secrets in namespaces that do not belong to the annotated project's cluster; secrets appearing in namespaces owned by low-privilege users that should not have access to those secrets.
• Namespace Annotations: Namespaces with field.cattle.io/projectId values referencing projects from foreign clusters (cluster ID prefix mismatch between the namespace's cluster and the annotation value).

SUSE has released Rancher v2.15.1, which fixes this vulnerability by updating the secretsController to validate that the field.cattle.io/projectId annotation references a project within the same cluster before propagating secrets. Administrators should upgrade to Rancher v2.15.1 or later as the primary remediation. No configuration-based workaround is documented; upgrading is the recommended and only confirmed fix (Rancher v2.15.1 Release).

The vulnerability was noted in automated CVE tracking feeds and aggregators shortly after publication, including VulDB, CVEFeed, and Bluesky CVE notification accounts. A blog post on hol.org specifically covered the cross-cluster project secret leak aspect of the vulnerability. Community reaction has been limited, consistent with the low EPSS score and absence of active exploitation (Feedly).