CVE-2026-93538 in Rancher
Summary
by MITRE • 09/28/2026
A cross-tenant authorization issue was discovered in SUSE Rancher Fleet. During agent-initiated cluster registration, cluster labels supplied by the registering agent, including labels in the reserved management.cattle.io/ namespace such as the cluster display name label, were applied to the resulting upstream Cluster object. Because Fleet resolves GitRepo and Bundle targets from those cluster labels, a party able to register a cluster into a Fleet workspace namespace shared with other tenants could cause its own cluster to satisfy targeting rules that administrators intended for a different cluster. This affects SUSE Rancher Fleet 0.16 before 0.16.1, 0.15 before 0.15.6, 0.14 before 0.14.10, 0.13 before 0.13.15, 0.12 before 0.12.19 and older versions.
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Analysis
by VulDB Data Team • 09/28/2026
A critical cross-tenant authorization vulnerability has been identified within SUSE Rancher Fleet, specifically affecting agent-initiated cluster registration processes. This flaw stems from the system's handling of metadata supplied by registering agents during the onboarding phase. When an external cluster attempts to register with a Fleet workspace namespace that is shared among multiple tenants or logical partitions, the fleet controller accepts and applies all labels provided in the request payload without sufficient validation against tenant boundaries. This includes labels residing within reserved namespaces such as management.cattle.io/, which are intended for internal system use rather than user-defined configuration. The vulnerability allows an attacker to inject specific label values into the cluster registration process that override or mimic attributes belonging to other clusters, effectively manipulating how Fleet identifies and targets resources for deployment.
The operational impact of this flaw is significant due to the central role labels play in SUSE Rancher Fleet's targeting logic. Fleet relies heavily on cluster labels to resolve GitRepo and Bundle targets, determining which configuration manifests should be deployed to which managed clusters. By injecting malicious or misleading labels into a registered upstream Cluster object, an adversary can cause their own cluster to satisfy targeting rules that were explicitly intended for a different tenant’s cluster. This misalignment means that sensitive deployment configurations, potentially containing proprietary code, infrastructure definitions, or security policies meant for one organization, could be inadvertently applied to another organization's environment. Such unauthorized configuration drift poses severe risks including data exfiltration, service disruption, and lateral movement within multi-tenant Kubernetes environments where strict isolation is required.
From a classification perspective, this vulnerability aligns with CWE-269 Improper Privilege Escalation as it allows an actor to gain access to resources or functions reserved for others by exploiting the trust relationship between the agent and the controller. Furthermore, it relates to CWE-732 Incorrect Permission Assignment for Critical Resource because the system fails to enforce proper access controls on metadata fields that dictate resource targeting. In terms of attack vectors, this falls under ATT&CK technique T1098.004 SSH Authorized Key Manipulation if used in conjunction with credential theft, but more accurately maps to T1537 Transfer Data to Cloud Account as it involves manipulating cloud-native configuration states across tenant boundaries. The flaw represents a failure in input validation and authorization checks specific to multi-tenancy contexts within container orchestration platforms.
To mitigate this risk, organizations running affected versions of SUSE Rancher Fleet must upgrade immediately to patched releases. Specifically, users should update to version 0.16.1 or later for the 0.16 branch, 0.15.6 or later for the 0.15 branch, 0.14.10 or later for the 0.14 branch, 0.13.15 or later for the 0.13 branch, and 0.12.19 or later for the 0.12 branch. Older versions are also susceptible and should be upgraded to their respective latest stable releases that include this fix. Until upgrades can be performed, administrators should restrict access to Fleet workspace namespaces to only trusted agents and monitor cluster registration events for unusual label injections. Implementing strict network policies and validating agent identities before allowing them to register clusters into shared workspaces can provide additional layers of defense against exploitation attempts.