High [CVE-2026-66787] cross-cluster DNS spoofing via unvalidated EndpointSlice and ServiceImport IPs

A flaw was found in the lighthouse component of Red Hat Advanced Cluster Management for Kubernetes. This vulnerability stems from insufficient validation of advertised IP addresses within EndpointSlice objects.

A compromised spoke cluster can exploit this by creating EndpointSlices with attacker-controlled IP addresses, causing other clusters' lighthouse DNS to redirect legitimate service traffic to malicious endpoints.

This enables a remote attacker to conduct transparent Man-in-the-Middle (MITM) attacks on cross-cluster service communications, potentially leading to unauthorized information disclosure and data manipulation.

By creating unvalidated EndpointSlice objects with attacker-controlled IP addresses, a malicious actor can redirect legitimate service traffic between clusters, enabling transparent Man-in-the-Middle attacks without altering the target service. Red Hat severity: Important — CVSS 8.7 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N).

Weakness: CWE-345. Red Hat does not currently list a fixing RHSA for this CVE.

Affected product named by the advisory: Red Hat Advanced Cluster Management for Kubernetes 2.