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

> Unauthenticated attackers can bypass authentication to access arbitrary internal services across managed clusters via the cluster-proxy-addon route.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 29 Sep 2026
- **Also known as:** GHSA-9855-9cch-x8mw

## What is CVE-2026-66794?

CVE-2026-66794 is a critical server-side request forgery vulnerability in Red Hat multicluster engine for Kubernetes 2.10, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-66794?


## How do I fix CVE-2026-66794?

No fix has been published for CVE-2026-66794 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66794 being exploited?

There is no known exploitation of CVE-2026-66794 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66794 and fix it if it is affected.

What it is: CVE-2026-66794 is a critical server-side request forgery vulnerability in Red Hat multicluster engine for Kubernetes 2.10, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-66794 in the wild and no public exploit code.

Affected product: Red Hat multicluster engine for Kubernetes 2.10. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66794/ (Markdown: https://insights.sbomify.com/CVE-2026-66794/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66794
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66794
- OSV: https://osv.dev/vulnerability/CVE-2026-66794

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66794/
Summaries are generated and may contain mistakes; the official description above is the record.