---
id: CVE-2026-66794
title: >-
  A flaw was found in the `cluster-proxy-addon` component of Multicluster Engine
  for Kubernetes
summary: >-
  A flaw was found in the `cluster-proxy-addon` component of Multicluster Engine
  for Kubernetes. This vulnerability allows an unauthenticated attacker, who can
  access the user-facing route, to bypass authentication and authorization
  checks…
severity: critical
cvss: 9.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N'
cwe:
  - CWE-918
vendor: Red Hat
product: multicluster-engine/cluster-proxy-addon-rhel9
affected:
  - multicluster-engine/cluster-proxy-addon-rhel9 (all versions)
  - multicluster-engine/cluster-proxy-rhel9 (all versions)
  - multicluster-engine/cluster-proxy-rhel9 (all versions)
  - multicluster-engine/cluster-proxy-addon-rhel9 (all versions)
  - multicluster-engine/cluster-proxy-addon-rhel9 (all versions)
  - multicluster-engine/cluster-proxy-addon-rhel9 (all versions)
published: '2026-08-19'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T13:17:21.050'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66794'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:59556'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:59557'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:59558'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:59559'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:59579'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:59593'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2026-66794'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2507539'
    label: secalert@redhat.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66794.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-66794'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66794'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-08-21T19:33:05.335178Z'
epss: 0.00621
epssPercentile: 0.47463
ingestedAt: '2026-09-05T19:43:55.383Z'
patched:
  - multicluster_engine_for_kubernetes 2.11
  - multicluster_engine_for_kubernetes 2.17
  - multicluster_engine_for_kubernetes 2.1
  - multicluster_engine_for_kubernetes 2.6
  - multicluster_engine_for_kubernetes 2.8
  - multicluster_engine_for_kubernetes 2.9
---

## Overview

A flaw was found in the `cluster-proxy-addon` component of Multicluster Engine for Kubernetes. This vulnerability allows an unauthenticated attacker, who can access the user-facing route, to bypass authentication and authorization checks. By manipulating URL path segments, the attacker can proxy requests to arbitrary services across any managed cluster. This enables unauthorized access to internal services that would otherwise be protected, potentially leading to information disclosure or further compromise of the cluster environment.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:59556** · Red Hat · fixed in: multicluster engine for Kubernetes 2.11 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59556)
- **RHSA-2026:59593** · Red Hat · fixed in: multicluster engine for Kubernetes 2.17 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59593)
- **RHSA-2026:59557** · Red Hat · fixed in: multicluster engine for Kubernetes 2.1 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59557)
- **RHSA-2026:59579** · Red Hat · fixed in: multicluster engine for Kubernetes 2.6 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59579)
- **RHSA-2026:59558** · Red Hat · fixed in: multicluster engine for Kubernetes 2.8 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59558)
- **RHSA-2026:59559** · Red Hat · fixed in: multicluster engine for Kubernetes 2.9 · released 2026-08-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:59559)