CVE-2025-2786 is a medium-severity vulnerability affecting Tempo Operator, a Kubernetes operator used to deploy TempoStack or TempoMonolithic instances. The vulnerability arises because when a user deploys these instances, the operator automatically creates a ServiceAccount along with a ClusterRole and ClusterRoleBinding. A user who has full access to their own Kubernetes namespace can extract the token associated with this ServiceAccount. With this token, the user can submit TokenReview and SubjectAccessReview API requests to the Kubernetes API server. These requests allow the user to query and reveal information about other users' permissions within the cluster. Importantly, this flaw does not permit privilege escalation or impersonation of other users, but it does expose sensitive authorization data that could be leveraged for reconnaissance and planning of further attacks. The vulnerability has a CVSS 3.1 base score of 4.3, reflecting a low impact on confidentiality, no impact on integrity or availability, and requiring privileges within the namespace but no user interaction. No known exploits are currently reported in the wild, and no patches or fixes have been linked yet. The issue was publicly disclosed in early April 2025, with the vulnerability reserved in late March 2025 by Red Hat. This vulnerability highlights a risk in multi-tenant Kubernetes environments where namespace-level users can gain insight into cluster-wide permission structures, potentially aiding attackers in crafting more targeted privilege escalation or lateral movement attacks in the future.

For European organizations using Tempo Operator to manage their Kubernetes deployments, this vulnerability poses a risk primarily in environments where multiple teams or tenants share the same cluster but are isolated by namespaces. The exposure of permission information could allow malicious insiders or compromised users to map out access controls and identify privileged accounts or sensitive roles. While direct privilege escalation is not possible through this vulnerability alone, the information disclosure can facilitate more effective social engineering, targeted attacks, or exploitation of other vulnerabilities. Organizations in sectors with strict data protection regulations such as finance, healthcare, and critical infrastructure could face compliance risks if attackers leverage this information to escalate attacks. Additionally, cloud service providers and managed Kubernetes platforms operating in Europe may be impacted if they use Tempo Operator and allow namespace-level user access. The vulnerability could undermine trust in multi-tenant Kubernetes environments and increase the attack surface for threat actors targeting European enterprises.

To mitigate this vulnerability, European organizations should take several specific actions beyond generic Kubernetes security best practices: 1) Restrict namespace-level user permissions to the minimum necessary, avoiding granting full namespace access unless absolutely required. 2) Monitor and audit the creation and usage of ServiceAccounts, ClusterRoles, and ClusterRoleBindings created by Tempo Operator deployments to detect anomalous token extraction or API requests related to TokenReview and SubjectAccessReview. 3) Implement network policies and API server request filtering to limit which users or service accounts can perform TokenReview and SubjectAccessReview requests. 4) Consider deploying Tempo Operator in isolated clusters or namespaces with strict access controls to reduce the risk of cross-tenant information leakage. 5) Stay updated with Tempo Operator releases and apply patches promptly once available. 6) Employ runtime security tools that can detect suspicious Kubernetes API calls or token usage patterns indicative of reconnaissance activity. 7) Educate Kubernetes administrators and developers about the risks of over-permissioned ServiceAccounts and the importance of least privilege principles in multi-tenant environments.