Kargo's `GetConfig()` and `RefreshResource()` API endpoints allow unauthenticated access

Impact

A bug was found with authentication checks on the GetConfig() API endpoint. This allowed unauthenticated users to access this endpoint by specifying an Authorization header with any non-empty Bearer token value, regardless of validity. This vulnerability did allow for exfiltration of configuration data such as endpoints for connected Argo CD clusters. This data could allow an attacker to enumerate cluster URLs and namespaces for use in subsequent attacks.

Additionally, the same bug affected the RefreshResource endpoint. This endpoint does not lead to any information disclosure, but could be used by an unauthenticated attacker to perform a denial-of-service style attack against the Kargo API. RefreshResource sets an annotation on specific Kubernetes resources to trigger reconciliations. If run on a constant loop, this could also slow down legitimate requests to the Kubernetes API server.

This vulnerability was identified by security researchers, and there are no known reports of exploitation in the wild.

Patches

This problem has been patched in the previous 3 versions of Kargo. Based on our information, almost all users are on one of these versions. If for some reason you cannot upgrade from an earlier version, please reach out to us.

Workarounds

There are no workarounds for this issue, so it is highly recommended to upgrade at the earliest possible

Additional details

This issue was caused by fallback logic in token authentication. The majority of Kargo endpoints are backed by Kubernetes objects, and for these endpoints, unrecognized token types are passed to the Kubernetes API for validation. However, the affected endpoints do not use Kubernetes or used an internal client not subject to authentication, so unrecognized tokens had no validation fallback. As a result, any request with a non-empty Bearer token in the Authorization header was incorrectly treated as authorized.