Affected: Bitnami: flux

Flux is an open and extensible continuous delivery solution for Kubernetes. Versions prior to 0.35.0 are subject to a Denial of Service. Users that have permissions to change Flux’s objects, either through a Flux source or directly within a cluster, can provide invalid data to fields `.spec.interval` or `.spec.timeout` (and structured variations of these fields), causing the entire object type to stop being processed. This issue is patched in version 0.35.0. As a workaround, Admission controllers can be employed to restrict the values that can be used for fields `.spec.interval` and `.spec.timeout`, however upgrading to the latest versions is still the recommended mitigation.

Flux is an open and extensible continuous delivery solution for Kubernetes. Versions prior to 0.35.0 are subject to a Denial of Service. Users that have permissions to change Flux’s objects, either through a Flux source or directly within a cluster, can provide invalid data to fields `.spec.interval` or `.spec.timeout` (and structured variations of these fields), causing the entire object type to stop being processed. This issue is patched in version 0.35.0. As a workaround, Admission controllers can be employed to restrict the values that can be used for fields `.spec.interval` and `.spec.timeout`, however upgrading to the latest versions is still the recommended mitigation.

Affected: Go: github.com/fluxcd/flux2, Go: github.com/fluxcd/source-controller, Go: github.com/fluxcd/kustomize-controller, Go: github.com/fluxcd/helm-controller, Go: github.com/fluxcd/notification-controller, Go: github.com/fluxcd/image-automation-controller, Go: github.com/fluxcd/image-reflector-controller, Go: github.com/fluxcd/helm-controller/api, Go: github.com/fluxcd/image-automation-controller/api, Go: github.com/fluxcd/image-reflector-controller/api and 3 more

Flux controllers within the affected versions range are vulnerable to a denial of service attack. Users that have permissions to change Flux’s objects, either through a Flux source or directly within a cluster, can provide invalid data to fields `.spec.interval` or `.spec.timeout` (and structured variations of these fields), causing the entire object type to stop being processed.

The issue has two root causes: a) the Kubernetes type `metav1.Duration` not being fully compatible with the Go type `time.Duration` as explained on [upstream report](https://github.com/kubernetes/apimachinery/issues/131); b) lack of validation within Flux to restrict allowed values.

### Workarounds

Admission controllers can be employed to restrict the values that can be used for fields `.spec.interval` and `.spec.timeout`, however upgrading to the latest versions is still the recommended mitigation.

### Credits

This issue was reported by Alexander Block (@codablock) through the Flux security mailing list (as [recommended](https://fluxcd.io/security/#report-a-vulnerability)).

### For more information

If you have any questions or comments about this advisory:

- Open an issue in any of the affected repositories. - Contact us at the CNCF Flux channel.

### References

- https://github.com/kubernetes/apimachinery/issues/131