GHSA-5vvm-67pj-72g4

Summary

Kargo's authorization model includes a promote verb -- a non-standard Kubernetes "dolphin verb" -- 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 Stages 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.

Integrity Impact to Vulnerable System (VI): Low

The attacker can coerce a Stage into a state it might not otherwise transition to. This constitutes bounded state corruption within a single Project. Kargo itself continues to function correctly.

Availability Impact to Vulnerable System (VA): None

Promotion resources created by exploitation of this vulnerability consume the same controller resources as a legitimate Promotion would. A user with proper promote permissions could generate identical load. The vulnerability does not introduce any new avenue for resource exhaustion.

Confidentiality Impact to Subsequent Systems (SC): None

The vulnerability does not provide any mechanism for the attacker to read data from downstream systems.

Integrity Impact to Subsequent Systems (SI): Low

Critically, the attacker does not control the content of Freight resources without artifact repositories also having been compromised. In isolation, which is how vulnerabilities are scored, the worst consequence of a successful attack is downstream systems (e.g. Argo CD) deploying incorrect revisions of artifacts, which in some cases should have been rejected by bypassed segments of the promotion pipeline. Though the operational consequences land on subsequent systems, they are bounded by the attacker's inability to inject arbitrary content.

Availability Impact to Subsequent Systems (SA): None

The attack does not provide any mechanism to degrade the availability of downstream systems beyond what could be achieved with legitimately promoted Freight.

Mitigating Factors

• Only the REST API endpoints introduced in v1.9.0 are affected. The legacy gRPC API and the Kargo UI (which uses the gRPC API) correctly enforce the promote permission check and are not vulnerable.

• The window of affected versions is narrow: v1.9.0 through v1.9.2.

• Exploitation requires authentication to the Kargo API server and specific operational permissions (patch on freights/status or create on promotions). Anonymous or minimally privileged users cannot exploit this vulnerability.

• Impact is bounded to a single Project. The promote bypass does not enable cross-Project access or escalation beyond the namespace in which the attacker already holds the prerequisite permissions.

• There is no evidence of exploitation in the wild.