CVE-2022-39272: Improper use of metav1.Duration allows for Denial of Service in Flux Controllers
Summary
CVE-2022-39272: Denial of service in flux controllers in github.com/fluxcd modules. Affects github.com/fluxcd/helm-controller/api versions < 0.26.0. Fixed in 0.26.0. How to fix ↓
Also tracked for
- flux · Bitnami
- kustomize · Bitnami
- github.com/fluxcd/flux2 · Go
The same CVE-2022-39272 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Flux is an open-source tool that provides a declarative approach to managing Kubernetes resources. It allows users to automate the deployment and synchronization of container images and configuration files. Flux controllers, including source-controller, kustomize-controller, helm-controller, notification-controller, image-automation-controller, and image-reflector-controller, are components of Flux that handle specific tasks within the Kubernetes cluster.
Vulnerability Detail
Flux controllers within the affected versions range are vulnerable to a denial of service attack. Users with permissions to modify Flux's objects can exploit this vulnerability by providing invalid data to fields .spec.interval or .spec.timeout, causing the entire object type to stop being processed. The vulnerability stems from the incompatibility between the Kubernetes type metav1.Duration and the Go type time.Duration, as well as the lack of validation within Flux to restrict allowed values. This issue can lead to disruption of Flux operations and potentially impact the availability of the Kubernetes cluster.
How To Fix
Minimum fixed version
0.26.0
This is the first release that contains the fix.
go get github.com/fluxcd/helm-controller/api@v0.26.0Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
To implement an admission controller workaround, you can configure a validating admission webhook that intercepts requests to modify Flux objects and enforces restrictions on the values of the .spec.interval and .spec.timeout fields. This can be done by validating the incoming data against a predefined set of allowed values or by implementing custom logic to handle the validation. The specific implementation details will depend on the Kubernetes cluster setup and the admission controller framework being used.
Conclusion
The vulnerability in Flux controllers can be mitigated by upgrading to the latest versions or implementing an admission controller workaround. It is important to ensure compatibility with the correct types and validate the values of the vulnerable fields to prevent the exploitation of this vulnerability. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for github.com/fluxcd/helm-controller/api →
FAQ
Flux is an open-source tool that provides a declarative approach to managing Kubernetes resources. It automates the deployment and synchronization of container images and configuration files.
Flux controllers are components of Flux that handle specific tasks within the Kubernetes cluster. They include source-controller, kustomize-controller, helm-controller, notification-controller, image-automation-controller, and image-reflector-controller.
This vulnerability allows users with permissions to modify Flux's objects to disrupt Flux operations by providing invalid data to certain fields. This can lead to the entire object type being stopped from processing, potentially impacting the availability of the Kubernetes cluster.
The recommended mitigation is to upgrade to the latest versions of the affected Flux controllers. This ensures compatibility with the correct types and includes validation to prevent the use of invalid values.
Yes, an admission controller can be implemented to restrict the values that can be used for the vulnerable fields. This can be done by validating the incoming data against a predefined set of allowed values or by implementing custom logic to handle the validation.
