FluxCD source-controller up to 1.8.4 Sparse-Checkout Feature path traversal

Summaryinfo

A vulnerability was found in FluxCD source-controller up to 1.8.4. It has been rated as critical. The impacted element is an unknown function of the component Sparse-Checkout Feature. Performing a manipulation results in path traversal. This vulnerability is cataloged as CVE-2026-47680. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in FluxCD source-controller up to 1.8.4. This affects an unknown function of the component Sparse-Checkout Feature. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

The source-controller is a Kubernetes operator, specialised in artifacts acquisition from external sources such as Git, OCI, Helm repositories and S3-compatible buckets. In versions 0.0.17 through 1.8.4, an actor with the ability to influence the contents of a bucket referenced by a `Bucket` resource can cause source-controller to write fetched object data to paths outside the per-reconciliation working directory. The corruption surface is bounded by source-controller's own and downstream Flux controllers' digest verification: source-controller verifies stored artifact digests during reconciliation and rebuilds on divergence; consumers (kustomize-controller, helm-controller) verify the digest of fetched artifacts and reject mismatches. These checks prevent a manipulated artifact from reaching the cluster, but an attacker can still write files anywhere the source-controller pod has permission to write. Separately, a user with permission to create or update `GitRepository` resources can cause source-controller to test for the existence of paths outside the cloned repository. Because the result is exposed via the resource's status, this allows limited enumeration of file paths on the controller pod. This surface exists only on source-controller v1.6.0 and later, where the sparse-checkout feature was introduced. This vulnerability was fixed in source-controller v1.8.5. There is no in-product workaround. Users should upgrade to a patched version. As a defense-in-depth measure for the GitRepository sparse-checkout surface, a `ValidatingAdmissionPolicy` (or a third-party policy engine such as Kyverno or OPA Gatekeeper) can be deployed to reject `GitRepository` resources whose `.spec.sparseCheckout` entries contain `..` or absolute path segments.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-47680 since 05/19/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 1.8.5 eliminates this vulnerability.

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Productinfo

Vendor

• FluxCD

Name

• source-controller

Version

• 1.8.0
• 1.8.1
• 1.8.2
• 1.8.3
• 1.8.4

Website

• Product: https://github.com/fluxcd/source-controller/

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