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CVE-2021-41254 Detail

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.


Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score matches with CNA score
CNA:  GitHub, Inc.
Base Score:  8.8 HIGH
Vector:  CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: The NVD and the CNA have provided the same score. When this occurs only the CNA information is displayed, but the Acceptance Level icon for the CNA is given a checkmark to signify NVD concurrence.

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Hyperlink Resource
https://github.com/fluxcd/kustomize-controller/security/advisories/GHSA-35rf-v2jv-gfg7 Exploit  Mitigation  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') cwe source acceptance level NIST   Provider acceptance level GitHub, Inc.  

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Change History

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Quick Info

CVE Dictionary Entry:
CVE-2021-41254
NVD Published Date:
11/12/2021
NVD Last Modified:
11/17/2021
Source:
GitHub, Inc.