CVE-2026-73137 in Advanced Cluster Management for Kubernetes
Summary
by MITRE • 08/21/2026
A flaw was found in the multicloud-operators-subscription component of Red Hat Advanced Cluster Management (RHACM). A tenant with HelmRelease create permissions can exploit this vulnerability by manipulating the `secretRef.Namespace` field. This allows the `GetSecret()` function in the HelmRelease controller to fetch sensitive credentials from any namespace, which are then sent to an attacker-controlled Helm repository. This can lead to the exfiltration of credentials from arbitrary namespace Secrets, resulting in information disclosure.
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Analysis
by VulDB Data Team • 08/21/2026
The vulnerability identified within the multicloud-operators-subscription component of Red Hat Advanced Cluster Management represents a critical security flaw rooted in insufficient input validation and improper access control mechanisms. Specifically, this issue affects users who possess HelmRelease creation permissions within the managed cluster environment. The core technical deficiency lies in how the system handles the `secretRef.Namespace` field during the processing of Helm charts. When a tenant creates or modifies a HelmRelease object, they can specify which namespace contains the secret reference for chart values. However, the underlying implementation fails to restrict this lookup to only those namespaces where the user has legitimate read access privileges. This architectural oversight allows an attacker with relatively low-level permissions to bypass standard isolation boundaries between tenants and namespaces within the multi-tenant cluster architecture.
The operational mechanism of exploitation involves manipulating the `secretRef.Namespace` field in a HelmRelease manifest. By specifying a namespace that contains sensitive credentials but where the user does not have direct read access, the tenant triggers the `GetSecret()` function within the HelmRelease controller. This function proceeds to fetch the secret data from the specified arbitrary namespace without performing adequate authorization checks against the requesting user's permissions for that specific target namespace. Once retrieved, these secrets are typically used as values during chart rendering or installation processes. In a malicious scenario, an attacker can configure the Helm repository URL in their release manifest to point to a server they control. As part of standard Helm operations, such as fetching charts or verifying signatures, the system may transmit data associated with the secret reference. Consequently, sensitive credentials extracted from arbitrary namespaces are exfiltrated to the attacker-controlled infrastructure.
The impact of this vulnerability is severe, primarily characterized by unauthorized information disclosure and potential credential compromise. Since Kubernetes secrets often contain database passwords, API keys, TLS certificates, or cloud provider access tokens, their exposure can lead to a cascade of further security incidents. An adversary who obtains these credentials could gain unauthorized access to backend services, disrupt application availability, or escalate privileges within the cluster environment. This flaw effectively undermines the multi-tenancy model that RHACM is designed to enforce, allowing lower-privileged users to act as if they have broader permissions than granted by their role-based access control policies. The ability to read secrets from any namespace breaks the principle of least privilege and compromises the confidentiality guarantees expected in a managed Kubernetes environment.
From a classification perspective, this vulnerability aligns with CWE-284 Improper Access Control, specifically reflecting failures in authorization checks that allow users to bypass intended restrictions. It also relates closely to CWE-798 Use of Hard-coded Credentials if those secrets are static, but more accurately fits CWE-501 Trust Boundary Violation because the system fails to maintain proper isolation between different trust domains or namespaces. In terms of MITRE ATT&CK techniques, this behavior is indicative of T1530 Data from Cloud Storage Object and potentially T1078 Valid Accounts if the attacker uses stolen credentials for further lateral movement. The exploitation path demonstrates a classic case of insecure direct object references where the identifier (namespace name) is used to access resources without verifying ownership or permission rights.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Red Hat has addressed this issue in subsequent releases of Advanced Cluster Management, so updating the multicloud-operators-subscription component to a patched version is the primary recommendation. Administrators should ensure that all cluster management components are kept up-to-date with the latest security patches provided by the vendor. In environments where immediate patching is not feasible, network segmentation and strict firewall rules can help limit outbound connections from control plane nodes to unknown external repositories, reducing the risk of data exfiltration. Additionally, implementing rigorous auditing policies that monitor for unusual HelmRelease configurations or unexpected secret access patterns can aid in early detection of exploitation attempts. Future development should enforce stricter validation logic within the `GetSecret()` function to ensure it only retrieves secrets from namespaces where the requesting user explicitly holds read permissions, thereby closing this trust boundary violation at the code level.