CVE-2026-54745: CWE-284: Improper Access Control in kubeflow pipelines

Kubeflow Pipelines frontend prior to version 2.17.0 exposes an SSRF vulnerability via the /_proxy/ route implemented in frontend/server/proxy-middleware.ts. The _routePathWithReferer() function accepts attacker-controlled HTTP/HTTPS targets and passes their origin to createProxyMiddleware without host allowlisting or filtering for loopback, link-local, RFC1918, or cluster-local addresses. This proxy route bypasses authorization middleware even when ENABLE_AUTHZ=true and is reachable through multiple API proxy paths and crafted Referer headers. Attackers can forward arbitrary HTTP methods, headers (including Authorization, Cookie, X-Forwarded-For), and POST bodies to internal services, receiving upstream responses directly. This can expose cloud metadata credentials, Kubernetes or service APIs, and other cluster-internal endpoints to unauthorized read or modification. The vulnerability is resolved in Kubeflow Pipelines version 2.17.0.

The vulnerability allows unauthenticated attackers to perform server-side request forgery to internal services within the cluster or cloud environment. This can lead to unauthorized disclosure of sensitive information such as cloud metadata credentials and unauthorized access or modification of Kubernetes or other internal service APIs. The CVSS score of 10 indicates critical impact with full confidentiality, integrity, and availability compromise possible.

A fix is available in Kubeflow Pipelines version 2.17.0. Users should upgrade to version 2.17.0 or later to remediate this vulnerability. Until upgraded, restricting network access to the frontend and applying additional network-level controls may reduce exposure, but the primary remediation is upgrading to the fixed version.