CVE-2026-23634: Pepr Overly Permissive RBAC ClusterRole in Admin Mode
Pepr is a type safe K8s middleware. Prior to 1.0.5 , Pepr defaults to a cluster-admin RBAC configuration and does not explicitly force or enforce least-privilege guidance for module authors. The default behavior exists to make the “getting started” experience smooth: new users can experiment with Pepr and create resources dynamically without needing to pre-configure RBAC. This vulnerability is fixed in 1.0.5.
Other sources
Severity: LOW Target: /workspace/pepr/src/lib/assets/rbac.ts Endpoint: Kubernetes RBAC configuration Method: Deployment
Response / Rationale Pepr defaults to rbacMode: "admin" because the initial experience is designed to be frictionless for new users. This mode ensures that users can deploy and run the default hello-pepr.ts module without needing to understand or pre-configure RBAC rules.
It’s important to note that hello-pepr.ts is intended strictly as a demo to showcase Pepr features and workflow. It is not intended for production use, and the documentation explicitly calls out that admin RBAC should not be used in production environments.
That said, if a user skips the documentation and does not review the npx pepr build options, they could deploy a module with broader privileges than necessary.
We consider this low severity because Pepr is a framework: the module author is ultimately responsible for selecting the appropriate RBAC scope for their module and environment as each module has different RBAC needs and requirements.
Our security focus is on ensuring the Pepr controller and runtime components operate securely within Kubernetes, while still allowing developers the flexibility to build modules with the access they require.
In order to fix this we will warn the user in logs that the default ClusterRole is cluster-admin and that it is not recommended for production.
How this can be exploited
This is not an inherently exploitable CVE in the traditional sense. It is being flagged because Pepr defaults to a cluster-admin RBAC configuration and does not explicitly force or enforce least-privilege guidance for module authors.
The default behavior exists to make the “getting started” experience smooth: new users can experiment with Pepr and create resources dynamically without needing to pre-configure RBAC.
Remediation: scope RBAC appropriately before deploying to production. Running:
bash npx pepr build --rbac-mode=scoped
generates the minimum RBAC required for the controller/informer to watch resources. Any additional permissions must be added based on the specific Kubernetes resources and CRUD operations performed by the module
— GitHub
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23634?
CVE-2026-23634 is classified as a high severity vulnerability due to the overly permissive RBAC configuration allowing unrestricted access.
How do I fix CVE-2026-23634?
To fix CVE-2026-23634, upgrade Pepr to version 1.0.5 or later to enforce least-privilege guidance.
What impact does CVE-2026-23634 have on Kubernetes environments?
CVE-2026-23634 can lead to unauthorized access and control over Kubernetes resources due to default cluster-admin permissions.
Who is affected by CVE-2026-23634?
CVE-2026-23634 affects users of Pepr prior to version 1.0.5 who have implemented the middleware in their Kubernetes environments.
Is there a workaround for CVE-2026-23634 before upgrading?
There are no official workarounds for CVE-2026-23634; upgrading to the latest version is the recommended approach.