CVE-2026-18674 is a vulnerability in Kong Inc.'s Kong Mesh affecting specific versions where the global control plane incorrectly attributes resources received over the zone-to-global KDS sync using a sender-controlled identifier rather than the authenticated zone identity. This flaw allows an authenticated zone to inject, attribute, and overwrite resources in another zone's namespace, resulting in a cross-zone isolation bypass.
When kuma-dp is started against an HTTPS control plane and the operator did not pass a CA certificate, the data plane connects with TLS peer verification disabled, and the dataplane authentication token is sent over that unverified connection.
An on-path actor can intercept the dataplane authentication token and impersonate the control plane to the data plane, injecting a forged bootstrap configuration and taking over the proxy.
When an operator adds an HTTPS control plane profile to kumactl without providing a CA certificate, kumactl disables TLS verification and sends API tokens over the unverified connection.
An attacker on the network path between the operator and the control plane can intercept user or admin API tokens and then act against the control plane as that user.
In Kong Mesh running in universal mode with a MeshIdentity whose SPIFFE ID path template derives from the dataplane's kuma.io/workload label, the XDS authenticator in kuma-cp validates that label only when the dataplane token is bound to a workload. Workload binding is optional, so a dataplane presenting a tags-bound token can register with kuma.io/workload set to any value and obtain another workload's SPIFFE identity.
The default kuma-cp configuration in Kong Mesh reveals the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. Due to a CORS misconfiguration a cross-origin fetch() from a malicious page returns the admin JWT and signing material.
The dataplane token validator in kuma-cp performs an unchecked Go type assertion on the JWT kid header. A token whose kid is a JSON number decodes as a float64 and triggers a runtime panic before any signature, claims, or authorization check runs.
The panic terminates the entire kuma-cp process, HTTP API, the health and readiness endpoints, and xDS. Unauthenticated access to the dataplane gRPC server can trigger the crash with a malformed token
A single request is a transient interruption; sustaining an outage requires repeated requests.
When kuma-dp is configured with the Envoy admin API on a Unix domain socket, which is the default, its readiness service on TCP port 9902 - bound to all interfaces - forwards almost the entire Envoy admin API to any caller that can reach the port, with no authentication.
An attacker with network access to a data plane's port 9902, for example another pod on the cluster network, can read Envoy and data plane configuration without credentials: config dumps, cluster and listener lists, stats, and the mesh trust bundle. Exposure is read-only - destructive Envoy admin actions are blocked and private keys are not exposed.