GitHub Security Advisory: GHSA-7g9x-cp9g-92mr
Package: github.com/akuity/kargo (GO)
Severity: CRITICAL (CVSS 0.0)
CWE: CWE-863: Incorrect Authorization
Vulnerable versions: >= 1.9.0-rc.1, < 1.9.3
Patched in: 1.9.3

Summary: Kargo has an Authorization Bypass Vulnerability in Batch Resource Creation API Endpoints

Details:
## Summary

The batch resource creation endpoints of both Kargo's legacy gRPC API and newer REST API accept multi-document YAML payloads. When either endpoint creates a `Project` resource, creation of subsequent resources from that same payload belonging in that Project's underlying Kubernetes namespace, by design, proceeds using the API server's own permissions. The creator of a new Project automatically becomes its administrator, but those permissions are granted asynchronously by the management controller. The design choice to create the affected resources using the API server's own permissions averts a race and is contextually appropriate.

Specially crafted payloads can manifest a bug present in the logic of both endpoints to inject arbitrary resources (of specific types only) into the underlying namespace of an _existing_ Project using the API server's own permissions when that behavior was _not_ intended. Critically, an attacker may exploit this as a vector for elevating their own permissions, which can then be leveraged to achieve remote code execution or secret exfiltration. Exfiltrated artifact repository credentials can be leveraged, in turn, to execute further attacks.

In some configurations of the Kargo control plane's underlying Kubernetes cluster, elevated permissions may additionally be leveraged to achieve remote code execution or secret exfiltration using `kubectl`. This can reduce the complexity of the attack, however, worst case scenarios remain entirely achievable even without this.

## Base Metrics

The following sections provide the rationale for the values selected for each of CVSS v4's base metrics.

### Attack Vector (AV): Network

The affected endpoints are served by the Kargo API server over HTTP/HTTPS. No local or physical access is required.

### Attack Complexity (AC): Low

Exploitation requires only a specially crafted YAML payload sent to an affected API endpoint.

### Attack Requirements (AT): None

No specific environmental conditions are required beyond those that are typical for any Kargo instance.

### Privileges Required (PR): Low

The attack relies only on the ability to authenticate to the Kargo API server along with basic permissions that are typically granted to all Kargo users.

### User Interaction (UI): None

The attack is fully automated via API calls. No other user needs to take any action.

### Confidentiality Impact to Vulnerable System (VC): High

Elevated permissions enable secret exfiltration from any Kargo Project.

### Integrity Impact to Vulnerable System (VI): High

Elevated permissions enable tampering, up to and including remote code execution, as well as secret exfiltration from any Kargo Project. Project secrets often include credentials having write permissions to GitOps repositories. Such secrets may enable pushing configurations that impact the integrity of the vulnerable system, including Kargo Projects, Kargo control plane components, and the Kargo control plane's underlying Kuber