CVE-2026-18381 in Cost Management Metrics Operator
Summary
by MITRE • 07/30/2026
A flaw was found in the koku-metrics-operator for Red Hat OpenShift. The operator's CostManagementMetricsConfig custom resource allows a user able to edit the CR to specify an arbitrary upload URL. The operator attaches its own Kubernetes service-account bearer token to queries sent to this user-controlled URL, allowing the attacker to obtain the token.
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Analysis
by VulDB Data Team • 07/30/2026
This vulnerability resides within the koku-metrics-operator component of Red Hat OpenShift's cost management functionality, representing a critical authorization and authentication flaw that directly enables credential theft. The issue stems from improper input validation within the CostManagementMetricsConfig custom resource implementation, where user-controlled inputs are directly incorporated into outbound HTTP requests without adequate sanitization or access control verification. The operator's design pattern inadvertently creates a trust relationship with user-defined endpoints, allowing malicious actors with edit permissions on the custom resource to manipulate the target upload URL. This flaw specifically enables privilege escalation through token hijacking, as the operator automatically appends its own Kubernetes service-account bearer token to every request sent to the specified URL, effectively providing attackers with legitimate credentials that can be used for further exploitation.
The technical mechanism of this vulnerability aligns with CWE-20: Improper Input Validation and CWE-352: Cross-Site Request Forgery, though it manifests specifically within Kubernetes custom resource definitions rather than traditional web applications. Attackers can leverage this weakness by crafting malicious CostManagementMetricsConfig resources that redirect traffic to attacker-controlled endpoints, where the service-account token is then captured during the HTTP request process. The operational impact extends beyond simple credential theft, as these tokens typically possess broad permissions within the Kubernetes cluster, potentially enabling lateral movement, privilege escalation, and persistent access to cluster resources. The vulnerability's exploitation requires only edit access to the specific custom resource, making it particularly dangerous in environments where least-privilege principles are not strictly enforced.
This flaw directly maps to several ATT&CK techniques including T1566.002: Phishing for Information, T1528: Steal Application Access Token, and T1078.004: Valid Accounts. The attack chain typically begins with an attacker obtaining edit privileges on the custom resource through various means such as compromised user credentials, misconfigured RBAC policies, or social engineering campaigns. Once the malicious URL is configured, the operator's automatic token attachment creates a seamless credential harvesting mechanism that requires minimal effort from the attacker. The stolen tokens can then be used to perform cluster-wide operations including pod creation, secret access, network policy modifications, and potentially even privilege escalation to cluster-admin roles if the service account possesses elevated permissions. Organizations with insufficient monitoring of custom resource changes may remain unaware of this attack vector until significant damage has occurred.
Mitigation strategies must address both the immediate vulnerability and broader architectural security concerns. The most effective immediate solution involves implementing strict input validation on all user-controllable fields within custom resources, particularly those that influence outbound network requests. Organizations should enforce principle of least privilege by ensuring service accounts possess minimal necessary permissions and implement RBAC policies that restrict edit access to custom resources. Additionally, deploying runtime monitoring solutions capable of detecting unauthorized custom resource modifications and network requests to suspicious endpoints provides crucial detection capabilities. The implementation of Kubernetes admission controllers or operator-specific validation hooks can prevent malicious configurations from being applied in the first place. Regular security assessments should include reviewing all custom resources for potential trust relationships that could be exploited and ensuring proper token management practices are implemented across the cluster infrastructure.