GitHub Security Advisory: GHSA-5vvm-67pj-72g4
Package: github.com/akuity/kargo (GO)
Severity: MODERATE (CVSS 0.0)
CWE: CWE-862: Missing Authorization
Vulnerable versions: >= 1.9.0, < 1.9.3
Patched in: 1.9.3

Summary: Kargo has Missing Authorization Vulnerabilities in Approval & Promotion REST API Endpoints

Details:
## Summary

Kargo's authorization model includes a `promote` verb -- a non-standard Kubernetes ["dolphin verb"](https://www.aquasec.com/blog/kubernetes-verbs/) -- that gates the ability to advance `Freight` through a promotion pipeline. This verb exists to separate the ability to _manage_ promotion-related resources from the ability to _trigger_ promotions, enabling fine-grained access control over what is often a sensitive operation.

The `promote` verb is correctly enforced in Kargo's legacy gRPC API. However, three endpoints in the newer REST API omit this check, relying only on standard Kubernetes RBAC for the underlying resource operations (`patch` on `freights/status` or `create` on `promotions`). This permits users who hold those standard permissions -- but who were deliberately _not_ granted `promote` -- to bypass the intended authorization boundary.

The affected endpoints are:

1. `POST /v1beta1/projects/{project}/freight/{freight}/approve`

    Approves `Freight` for promotion to a specific `Stage`.

    The endpoint is intended to require both `patch` permission on `Freight` status and `promote` permission on the target `Stage`, but asserts only the former.

2. `POST /v1beta1/projects/{project}/stages/{stage}/promotions`

    Promotes `Freight` to a specific `Stage`.

    The endpoint is intended to require both `create` permission on `Promotion` resources and `promote` permission on the target `Stage`, but asserts only the former.

3. `POST /v1beta1/projects/{project}/stages/{stage}/promotions/downstream`

    Promotes `Freight` to all `Stage`s immediately downstream of a given `Stage`.

    The endpoint is intended to require both `create` permission on `Promotion` resources and `promote` permission on each downstream `Stage`, but asserts only the former.

## 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 part of Kargo's newer REST API, which is served over HTTP/HTTPS. (The analogous endpoints of the legacy gRPC API correctly check `promote` permission and are not affected.) No local or physical access is required.

### Attack Complexity (AC): Low

The attack requires only well-formed API requests to the affected endpoints.

### Attack Requirements (AT): None

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

### Privileges Required (PR): Low

The attacker must hold permissions to patch `Freight` status and/or create `Promotion` resources. These are standard operational permissions commonly granted to some Kargo users and do not represent what CVSS formally considers administrative or elevated access.

### 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): None

The vulnerability does not expose any data from the Kargo control plane