CVE-2021-41254 Information

Description

kustomize-controller is a Kubernetes operator specialized in running continuous delivery pipelines for infrastructure and workloads defined with Kubernetes manifests and assembled with Kustomize. Users that can create Kubernetes Secrets Service Accounts and Flux Kustomization objects could execute commands inside the kustomize-controller container by embedding a shell script in a Kubernetes Secret. This can be used to run kubectl commands under the Service Account of kustomize-controller thus allowing an authenticated Kubernetes user to gain cluster admin privileges. In affected versions multitenant environments where non-admin users have permissions to create Flux Kustomization objects are affected by this issue. This vulnerability was fixed in kustomize-controller v0.15.0 (included in flux2 v0.18.0) released on 2021-10-08. Starting with v0.15 the kustomize-controller no longer executes shell commands on the container OS and the kubectl binary has been removed from the container image. To prevent the creation of Kubernetes Service Accounts with secrets in namespaces owned by tenants a Kubernetes validation webhook such as Gatekeeper OPA or Kyverno can be used.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Reference

https://github.com/fluxcd/kustomize-controller/security/advisories/GHSA-35rf-v2jv-gfg7

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

8.8